Curable Composition

ABSTRACT

The present invention has its object to provide a transparent curable composition which may be prepared as a one package formulation, and which is excellent in strength, elongation at break, weather resistance, and adhesiveness of the resultant cured product. 
     In addition, the present invention provides a curable composition which comprises 100 parts by weight of a vinyl polymer (I) the main chain of which is the product of living radical polymerization and which contains a crosslinkable silyl group, and 1 to 200 parts by weight of a micronized hydrophobic silica (II). Furthermore, the present invention also provides a curable composition which comprises 100 parts by weight of a vinyl polymer (I) the main chain of which is the product of living radical polymerization and which contains at least one crosslinkable silyl group, and 1 to 200 parts by weight of a graft copolymer (III) obtained by graft polymerization of a crosslinkable rubber-like acrylic ester polymer and a vinyl monomer.

TECHNICAL FIELD

The present invention relates to transparent curable composition whichcomprises a vinyl polymer (I) the main chain of which is the product ofliving radical polymerization and which contains at least onecrosslinkable silyl group, a micronized hydrophobic silica (II), or agraft copolymer (III) obtained by graft polymerization of acrosslinkable rubber-like acrylic ester polymer and a vinyl monomer.

BACKGROUND ART

Room temperature curable polymers, which are in liquid phase beforecuring and rubber-like elastic bodies after curing, are used foradhesives, sealing materials, gaskets, and the like. As typical roomtemperature curable sealing materials, urethane, silicone, modifiedsilicone, polysulfide and the like type sealing materials are known.

The sealing materials are used for various kinds of materials, e.g.,glass, metals, construction materials such as stone. In the case wherethey are used for glass or the like transparent materials, light reachesthe interface between glass and the sealing material through the grassand, if the sealing material is low in weather resistance, it isdeteriorated and therefore peeling in the interface between the glassand the sealing material is caused. Therefore, the silicone type sealingmaterial, which is excellent in weather resistance, has been used as asealing material for glass or the like transparent materials. However,the silicon type sealing material has a problem that a silicone compoundsuch as silicone oil bleeds out and pollutes the surroundings of thesealing material.

To solve the above-mentioned problem attributed to the silicone typesealing material, a method is proposed which uses a non-silicone typesealing material such as a modified silicone type sealing material and apolyisobutylene type sealing material having a reactive silyl group inplace of the silicone type sealing material (reference to Japanese KokaiPublication Hei-10-205013). Japanese Kokai Publication Hei-10-205013describes that the polyisobutylene type sealing material having areactive silyl group is usable as a sealing material for glass or thelike transparent materials. However, resin components of thepolyisobutylene type sealing material scarcely permeate water, so thatthe material is difficult to be used as so-called moisture-curingone-component type sealing material.

On the other hand, although having better weather resistance than theurethane type sealing material, the modified silicone type sealingmaterial is insufficient in long-term weather resistance. To improveweather resistance of the modified silicone type sealing material, amethod using (meth)acrylic polymers having a crosslinkable silyl groupin combination is disclosed (reference to Japanese Kokai PublicationSho-59-122541). The method failed to improve the weather resistance to asufficient extent to be used for transparent materials, however.

In the case of using the room temperature curable composition foradhesives, sealing materials, gaskets, or the like application, calciumcarbonate, talc, clay and/or the like are generally added mainly for thepurpose of reinforcement. However, in recent years, buildings with highgrade design have been constructed and, in the case where glass, acrylicboards, high-strength polycarbonates and/or the like transparentsubstrates are used, the sealing material is also required to have goodtransparency in some cases. Further, in these years, many sidinghousings using siding boards for the outer walls have been constructedand various colors are employed for the siding boards. The sealingmaterials to be used for the siding boards are those which are not somuch noticeable, and it is preferable to use sealing materials with thesame color as that of the siding boards. However, it is not preferred toproduce and store as many types of sealing materials corresponding tothose of the siding boards. If a semi-transparent sealing material isavailable, this, in its own, can be used to almost all of boards withvarious colors and make it possible to avoid vain stock of many kinds ofsealing materials. Further, since being used generally for rear faces ofsubstrates, adhesives are not required to be transparent. However, theadhesives come out and ruin the appearance in some cases, and thereforetransparent adhesives are desired. To ensure the transparency, fillersmainly composed of calcium carbonate, mentioned above, cannot be usedbecause they make the material opaque and selection of proper fillers isthus needed. In the case where the sealing material is used for glass orthe like transparent materials, the interface between the sealingmaterial and transparent material tends to be deteriorated easily by thelight though the transparent material and therefore, the sealingmaterial has to be very high in weather resistance. Further, in the casewhere the sealing material itself is transparent, light reaches even theinside of the sealing material, and therefore the sealing material isrequired to have further high weather resistance.

With respect to copolymerization products obtained by polymerization ofmonomers having polymerizable unsaturated bonds and/or macromonomersthereof with reactive silicone monomers and/or macromonomers thereof, inthe system where the above mentioned components are soluble, by using anoil-soluble polymerization initiator, a silicone-acrylic randomcopolymer is disclosed which has a melt-flow rate of 2 to 30 g/10 min.at 230° C. and 3.92×10⁵ Pa load and exhibits a luminous transmission of90% or higher when determined by absorptiometry before and after moldingof the copolymerization products (reference to Japanese KokaiPublication 2002-80548). However, this polymerization cannot realizehigh elongation at break, which is required for the sealing material tohave.

A moisture-curable adhesive composition is disclosed which comprises apolyoxypropylene type modified silicone resin containing an acrylicpolymer having a silicon-containing functional group, the curing agentthereof, a micronized hydrophobic silica, and an amino group-containingsilane coupling agent (reference to Japanese Kokai Publication2000-38560). Although this composition is excellent in transparency, thecured product obtained from the composition is insufficient inelongation at break and weather resistance.

Further, another kind of moisture-curable composition is disclosed whichcomprises 100 parts by weight of a mixture containing a copolymer themolecular chain of which is substantially composed of a (meth)acrylicalkyl ester monomer unit having an alkyl group of 1 to 8 carbon atomsand a (meth)acrylic alkyl ester monomer unit having an alkyl group of 10or more carbon atoms, said copolymer having a reactive silyl groupcrosslinkable by hydrolysis, and an oxyalkylene polymer having areactive silyl group crosslinkable by hydrolysis; and 2 to 300 parts byweight of a micronized hydrophobic silica of a particle size of 0.01 to300 μm (reference to Japanese Kokai Publication Hei-11-302527). Thecured product obtained from the composition is also insufficient inelongation at break and weather resistance.

SUMMARY OF THE INVENTION

The problem which the invention is to solve is to provide a transparentcurable composition and a sealing material excellent in weatherresistance, adhesiveness, strength, and elongation at break.

The present inventors found the following invention will overcome theabove-mentioned problems.

[1] A curable composition

which comprises 100 parts by weight of a vinyl polymer (I) the mainchain of which is the product of living radical polymerization and whichcontains at least one crosslinkable silyl group, and 1 to 200 parts byweight of a micronized hydrophobic silica (II).

[2] A curable composition

which comprises 100 parts by weight of a vinyl polymer (I) the mainchain of which is the product of living radical polymerization and whichcontains at least one crosslinkable silyl group, and 1 to 200 parts byweight of a graft copolymer (III) obtained by graft polymerization of acrosslinkable rubber-like acrylic ester polymer and a vinyl monomer.

[3] The curable composition according to [1] or [2]

wherein the vinyl polymer (I) has a molecular weight distribution ofless than 1.8.

[4] The curable composition according to any one of [1] to [3]

wherein a vinyl monomer constituting the main chain of the vinyl polymer(I) is mainly selected from the group consisting of (meth)acrylicmonomers, acrylonitrile monomers, aromatic vinyl monomers,fluorine-containing vinyl monomers and silicon-containing vinylmonomers.

[5] The curable composition according to any one of [1] to [4]

wherein the main chain of the vinyl polymer (I) is a (meth)acrylicpolymer.

[6] The curable composition according to any one of [1] to [5]

wherein the main chain of the vinyl polymer (I) is an acrylic polymer.

[7] The curable composition according to [6]

wherein the main chain of the vinyl polymer (I) is an acrylic esterpolymer.

[8] The curable composition according to any one of [1] to [7]

wherein the living radical polymerization for producing the main chainof the vinyl polymer (I) is the atom transfer radical polymerization.

[9] The curable composition according to [8]

wherein a transition metal complex used as the catalyst in the atomtransfer radical polymerization is one composed of a VII, VIII, IX, X,or XI group element in the periodic table as a central metal.

[10] The curable composition according to [9]

wherein the metal complex used as the catalyst is a complex composed ofcopper, nickel, ruthenium or iron as a central metal.

[11] The curable composition according to [10]

wherein the metal complex used as the catalyst is a complex of copper.

[12] The curable composition according to any one of [1] to [11]

wherein the crosslinkable silyl group of the vinyl polymer (I) isrepresented by the general formula 1:

[Si(R¹)_(2-b)(Y)_(b)O]_(l)—Si(R²)_(3-a)(Y)_(a)  (1)

{wherein, R¹ and R² are the same or different and each is an alkyl groupcontaining 1 to 20 carbon atoms, an aryl group containing 6 to 20 carbonatoms, an aralkyl group containing 7 to 20 carbon atoms or atriorganosiloxy group represented by (R′)₃SiO— (in which R′ represents aunivalent hydrocarbon group containing 1 to 20 carbon atoms and thethree R′ groups may be the same or different) and, when there are two ormore R¹ or R² groups, they may be the same or different; Y represents ahydroxyl group or a hydrolyzable group and, when there are two or more Ygroups, they may be the same or different; a represents 0, 1, 2 or 3, brepresents 0, 1 or 2, and l represents an integer of 0 to 19, providedthat the relation a+lb≧1 should be satisfied.}

[13] The curable composition according to any one of [1] to [12]

wherein the crosslinkable silyl group of the vinyl polymer (I) is at theterminus of the main chain.

[14] A curable composition

wherein the micronized hydrophobic silica (II) has a particle diameterof not greater than 0.02 μm.

[15] The curable composition according to any one of [1] to [14]

which further comprises a polyoxyalkylene polymer (IV) containing atleast one crosslinkable silyl group in an amount within the range of 0.1to 1,000 parts by weight per 100 parts by weight of the vinyl polymer(I).

[16] The curable composition according to any one of [1] to [14]

which comprises no polyoxyalkylene polymer (IV) containing acrosslinkable silyl group(s).

[17] The curable composition according to any one of [1] to [16]

which further comprises 0.1 to 20 parts by weight of a tin curingcatalyst (V) per 100 parts by weight of the vinyl polymer (I).

[18] An adhesive

which comprises the curable composition according to any one of [1] to[17].

[19] A sealing material

which comprises the curable composition according to any one of [1] to[17].

[20] A liquid gasket

which comprises the curable composition according to any one of [1] to[17].

[21] A coating material

which comprises the curable composition according to any one of [1] to[17].

Namely, the present invention relates to a curable composition whichcomprises a vinyl polymer (I) the main chain of which is the product ofliving radical polymerization and which contains at least onecrosslinkable silyl group, a micronized hydrophobic silica (II), and agraft copolymer (III) obtained by graft polymerization of acrosslinkable rubber-like acrylic ester polymer and a vinyl monomer.

The term “crosslinkable silyl group” as used herein means asilicon-containing group containing a hydroxyl or hydrolysable groupbound to a silicon atom and capable of being crosslinked under formationof a siloxane bond.

The curable composition of the invention may be prepared as a onepackage formulation, which can be cured by the reaction with themoisture in the air at room temperature, and is a transparent curablecomposition excellent in strength, elongation at break, weatherresistance, and adhesiveness of the resultant cured product. Further,said curable composition can be suitably used as a transparent adhesive,sealing material and the like.

DETAILED DESCRIPTION OF THE INVENTION

In the following, the curable composition of the invention is describedin detail.

<<Vinyl Polymer (I) Whose Main Chain is a Product of Living RadicalPolymerization>> <Main Chain>

A vinyl monomer which constitutes the main chain of vinyl polymer (I) ofthe present invention is not particularly limited, and any of variousmonomers can be used. Examples of the vinyl monomer include(meth)acrylic acid monomers, such as (meth)acrylic acid,methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate,isopropyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate,tert-butyl(meth)acrylate, n-pentyl(meth)acrylate, n-hexyl(meth)acrylate,cyclohexyl(meth)acrylate, n-heptyl(meth)acrylate, n-octyl(meth)acrylate,2-ethylhexyl(meth)acrylate, nonyl(meth)acrylate, decyl(meth)acrylate,dodecyl(meth)acrylate, phenyl(meth)acrylate, tolyl(meth)acrylate,benzyl(meth)acrylate, 2-methoxyethyl(meth)acrylate,3-methoxybutyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate,2-hydroxypropyl(meth)acrylate, stearyl(meth)acrylate,glycidyl(meth)acrylate, 2-aminoethyl(meth)acrylate,γ-(methacryloyloxypropyl)trimethoxysilane, ethylene oxide adduct of(meth)acrylic acid, trifluoromethylmethyl(meth)acrylate,2-trifluoromethylethyl(meth)acrylate,2-perfluoroethylethyl(meth)acrylate,2-perfluoroethyl-2-perfluorobutylethyl(meth)acrylate,2-perfluoroethyl(meth)acrylate, perfluoromethyl(meth)acrylate,diperfluoromethylmethyl(meth)acrylate,2-perfluoromethyl-2-perfluoroethylmethyl(meth)acrylate,2-perfluorohexylethyl(meth)acrylate,2-perfluorodecylethyl(meth)acrylate, and2-perfluorohexadecylethyl(meth)acrylate; aromatic vinyl monomers, suchas styrene, vinyltoluene, α-methylstyrene, chlorostyrene, andstyrenesulfonic acid and its salts; fluorine-containing vinyl monomers,such as perfluoroethylene, perfluoropropylene, and vinylidene fluoride;silicon-containing vinyl monomers, such as vinyltrimethoxysilane andvinyltriethoxysilane; maleic anhydride, maleic acid, and monoalkylesters and dialkyl esters of maleic acid; fumaric acid and monoalkyl anddialkyl esters of fumaric acid; maleimide monomers, such as, maleimide,methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide,hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide,phenylmaleimide, and cyclohexylmaleimide; acrylonitrile monomers, suchas acrylonitrile and methacrylonitrile; amido-containing vinyl monomers,such as acrylamide and methacrylamide; vinyl esters, such as vinylacetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinylcinnamate; alkenes, such as ethylene and propylene; conjugated dienes,such as butadiene and isoprene; and vinyl chloride, vinylidene chloride,allyl chloride, and allyl alcohol. These compounds may be used alone, orat least two may be copolymerized.

The main chain of the vinyl polymer (I) is preferably one produced bypolymerizing predominantly at least one monomer selected from the groupconsisting of (meth)acrylic monomers, acrylonitrile monomers, aromaticvinyl monomers, fluorine-containing vinyl monomers andsilicon-containing vinyl monomers. The term “predominantly” as usedherein means that the above-mentioned monomer accounts for not less than50 mole percent, preferably not less than 70 mole percent, of themonomer units constituting the vinyl polymer (I).

In particular, from the viewpoint of physical properties of a product,styrene monomers and (meth)acrylic monomers are preferred. Acrylatemonomers and methacrylate monomers are more preferred, acrylate monomersare further preferred, and butyl acrylate is further more preferred. Inthe present invention, these preferred monomers may be copolymerized,e.g., block-copolymerized, with another monomer. In this case, thecontent by weight of the preferred monomers is preferably 40% by weightor more. In the above expression, for example, the term “(meth)acrylicacid” means acrylic acid and/or methacrylic acid.

In those fields of application where rubber elasticity is required, thevinyl polymer (I) preferably has a glass transition temperature of roomtemperature or lower than the expected use temperature range, althoughthis is not critical.

The molecular weight distribution [ratio (Mw/Mn) of the weight averagemolecular weight (Mw) to the number average molecular weight (Mn)determined by gel permeation chromatography (GPC)] of vinyl polymer (I)of the present invention is not particularly limited, but the ratio ispreferably less than 1.8, further preferably 1.6 or less, andparticularly preferably 1.3 or less. In GPC measurement in the presentinvention, a number average molecular weight and the like may begenerally determined in terms of polystyrene using chloroform as amobile phase and a polystyrene gel column for measurement.

The number average molecular weight of vinyl polymer (I) of the presentinvention is not particularly restricted, and preferably in a range of500 to 1,000,000 and more preferably 5,000 to 50,000 with gel permeationchromatography.

<Method of Main Chain Synthesis>

In accordance with the invention, the method of synthesizing the vinylpolymer (I) is limited to a living radical polymerization techniqueamong controlled radical polymerization techniques, and the atomtransfer radical polymerization technique is preferred. This techniqueis described below.

Controlled Radical Polymerization

Radical polymerization processes are classified into a general radicalpolymerization process (free radical polymerization) in which a monomerhaving a specified functional group and a vinyl monomer are simplycopolymerized using an azo compound, a peroxide, or the like as apolymerization initiator, and a controlled radial polymerization processin which a specified functional group can be introduced at a controlledposition such as an end or the like.

The general radical polymerization process is a simple process, and amonomer having a specified functional group can be introduced into apolymer only stochastically. When a polymer with high functionality isdesired, therefore, a considerable amount of a monomer must be used.Conversely, use of a small amount of a monomer has the problem ofincreasing the ratio of a polymer in which the specified functionalgroup is not introduced. There is also the problem of producing only apolymer with a wide molecular weight distribution and high viscosity dueto free radical polymerization.

The controlled radical polymerization process is further classified intoa chain transfer agent process in which polymerization is performedusing a chain transfer agent having a specified functional group toproduce a vinyl polymer having the functional group at an end, and aliving radical polymerization process in which polymerizationpropagation termini propagate without causing termination reaction orthe like to produce a polymer having a molecular weight substantiallyequal to the design.

The chain transfer agent process is capable of producing a polymer withhigh functionality, but a considerable amount of a chain transfer agenthaving a specified functional group must be used relative to theinitiator, thereby causing an economical problem of the cost includingthe treatment cost. Like the general radical polymerization process, thechain transfer agent process also has the problem of producing only apolymer with a wide molecular weight distribution and high viscositybecause it is free radical polymerization.

It is true that the living radical polymer process belongs to a radicalpolymerization process which has a high polymerization rate and isdifficult to control because termination reaction easily occurs due toradical coupling or the like. However, unlike in the above-mentionedprocesses, in the living radical polymerization process, terminationreaction little occurs, a polymer having a narrow molecular weightdistribution (Mw/Mn of about 1.1 to 1.5) can be produced, and themolecular weight can be freely controlled by changing the charge ratioof the monomer to the initiator.

Therefore, the living radical polymerization process is capable ofproducing a polymer with a narrow molecular weight distribution and lowviscosity and introducing a monomer having a specified functional groupinto a substantially desired position. Thus, this process is morepreferred as a process for producing the vinyl polymer having thespecified functional group.

In a narrow sense, “living polymerization” means polymerization in whichmolecular chains propagate while maintaining activity at the termini.However, the living polymerization generally includes pseudo-livingpolymerization in which molecular chains propagate in equilibriumbetween deactivated and activated termini. The definition in the presentinvention includes the latter.

In recent, the living radical polymerization has been actively studiedby various groups. Examples of studies include a process using a cobaltporphyrin complex, as shown in Journal of American Chemical Society (J.Am. Chem. Soc.), 1994, vol. 116, p. 7943, a process using a radicalcapping agent such as a nitroxide compound, as shown in Macromolecules,1994, vol. 27, p. 7228, and an atom transfer radical polymerization(ATRP) process using an organic halide or the like as an initiator and atransition metal complex as a catalyst.

Among these living radical polymerization processes, the atom transferradical polymerization process in which a vinyl monomer is polymerizedusing an organic halide or a halogenated sulfonyl compound as aninitiator and a transition metal complex as a catalyst has theabove-mentioned characteristics of the living radical polymerization andalso has the characteristic that a terminus has a halogen or the like,which is relatively useful for functional group conversion reaction, andthe initiator and catalyst have high degrees of design freedom.Therefore, the atom transfer radical polymerization process is morepreferred as a process for producing a vinyl polymer having a specifiedfunctional group. Examples of the atom transfer radical polymerizationprocess include the processes disclosed in Matyjaszewski, et al.,Journal of American Chemical Society (J. Am. Chem. Soc.), 1995, vol.117, p. 5614, Macromolecules, 1995, vol. 28, p. 7901, Science, 1996,vol. 272, p. 866, WO96/30421, WO97/18247, WO98/01480 and WO98/40415,Sawamoto, et al., Macromolecules, 1995, vol. 28, p. 1721, and JapaneseKokai Publication Hei-09-208616 and Japanese Kokai PublicationHei-08-41117.

In the present invention, any one of these living radical polymerizationprocesses may be used without limitation, but the atom transfer radicalpolymerization process is preferred.

Hereinafter, the living radical polymerization will be described indetail. First, the controlled radical polymerization process using achain transfer agent, which may be used in the production of the vinylpolymers mentioned below, will be described. The radical polymerizationprocess using the chain transfer agent (telomer) is not particularlylimited, but examples of a process for producing a vinyl polymer havinga terminal structure suitable for the present invention include thefollowing two processes:

A process for producing a halogen-terminated polymer using a halogenatedhydrocarbon as the chain transfer agent as disclosed in Japanese KokaiPublication Hei-04-132706, and a method for producing a hydroxylgroup-terminated polymer using a hydroxyl group-containing mercaptane ora hydroxyl group-containing polysulfide or the like as the chaintransfer agent as disclosed in Japanese Kokai Publication Sho-61-271306,Japanese Patent Publication No. 2594402, and Japanese Kokai PublicationSho-54-47782.

Next, the living radical polymerization will be described.

First, the process using a nitroxide compound and the like as a radicalcapping agent will be described. This polymerization process generallyuses stable nitroxy free radical (═N—O.) as a radical capping agent.Preferred examples of such a compound include, but not limited to,nitroxy free radicals produced from cyclic hydroxyamines, such as2,2,6,6-substituted-1-piperidinyloxy radical and2,2,5,5-substituted-1-piperidinyloxy radical. As a substituent, an alkylgroup having 4 or less carbon atoms, such as methyl or ethyl, issuitable. Specific examples of a nitroxy free radical compound include,but not limited to, 2,2,6,6-tetramethyl-1-piperidinyloxy radical(TEMPO), 2,2,6,6-tetraethyl-1-piperidinyloxy radical,2,2,6,6-tetramethyl-4-oxo-1-piperidinyloxy radical,2,2,5,5-tetramethyl-1-pyrrolidinyloxy radical,1,1,3,3-tetramethyl-2-isoindolinyloxy radical, andN,N-di-tert-butylaminoxy radical. Instead of the nitroxy free radical,stable free radical such as galvinoxyl free radical may be used.

The radical capping agent is used in combination with the radicalgenerator. The reaction product of the radical capping agent and theradical generator possibly servers as a polymerization initiator topromote polymerization of an addition-polymerizable monomer. The ratiobetween both agents used is not particularly limited, but the amount ofthe radical generator is preferably 0.1 to 10 moles per mole of theradical capping agent.

As a radical generator, any one of various compounds can be used, but aperoxide capable of generating radical under a polymerizationtemperature is preferred. Examples of the peroxide include, but notlimited to, diacyl peroxides, such as benzoyl peroxide and lauroylperoxide; dialkyl peroxides, such as dicumyl peroxide and di-tert-butylperoxide; peroxycarbonates, such as diisopropyl peroxydicarbonate andbis(4-tert-butylcyclohexyl)peroxydicarbonate; and alkyl peresters, suchas tert-butyl peroxyoctoate and tert-butyl peroxybenzoate. Inparticular, benzoyl peroxide is preferred. Instead of the peroxide, aradical generator such as a radical generating azo compound, e.g.,azobisisobutyronitrile, may be used.

As reported in Macromolecules, 1995, 28, 2993, the alkoxyamine compoundshown below may be used as the initiator instead of a combination of theradical capping agent and the radical generator.

When the alkoxyamine compound is used as the initiator, the use of acompound having a functional group such as a hydroxyl group as shown inthe above figure produces a polymer having the functional group at anend. When this compound is used in the method of the present invention,a polymer having the functional group at an end is produced.

The conditions of polymerization using the nitroxide compound and/or thelike as the radical capping agent, such as the monomer, the solvent, thepolymerization temperature, and the like, are not limited. However,these conditions may be the same as those in atom transfer radicalpolymerization which will be described below.

Atom Transfer Radical Polymerization

Next, the atom transfer radical polymerization suitable as the livingradical polymerization of the present invention will be described.

The atom transfer radical polymerization uses, as the initiator, anorganic halide, particularly an organic halide having a highly reactivecarbon-halogen bond (e.g., a carbonyl compound having a halogen at anα-position, or a compound having a halogen at a benzyl position), or ahalogenated sulfonyl compound.

Specific examples of such a compound include the following:

C₆H₅—CH₂X, C₆H₅—C(H)(X)CH₃, and C₆H₅—C(X)(CH₃)₂

(wherein C₆H₅ is a phenyl group, X is chlorine, bromine, or iodine);R³—C(H)(X)—CO₂R⁴, R³—C(CH₃)(X)—CO₂R⁴, R³—C(H)(X)—C(O)R⁴, andR³—C(CH₃)(X)—C(O)R⁴(wherein R³ and R⁴ each is a hydrogen atom or an alkyl group, an arylgroup, or an aralkyl group having 1 to 20 carbon atoms; X is chlorine,bromine, or iodine); and

R³—C₆H₄—SO₂X

(wherein R³ is a hydrogen atom or an alkyl group, an aryl group, or anaralkyl group having 1 to 20 carbon atoms; X is chlorine, bromine, oriodine).

As the initiator of the atom transfer radical polymerization, an organichalide or halogenated sulfonyl compound having a functional group otherthan a functional group which initiates polymerization can be used. Inthis case, the resultant vinyl polymer has the functional group at oneof the main chain ends and a polymerization propagationterminal-structure of atom transfer radical polymerization at the otherend. Examples of such a functional group include alkenyl, crosslinkablesilyl, hydroxyl, epoxy, amino, and amido group.

Examples of an organic halide having an alkenyl group include, but notlimited to, compounds having the structure represented by the generalformula 2:

R⁶R⁷C(X)—R⁸—R⁹—C(R⁵)═CH₂  (2)

(wherein R⁵ is a hydrogen atom or a methyl group; R⁶ and R⁷ each is ahydrogen atom, an alkyl group, an aryl group or an aralkyl group having1 to 20 carbon atoms, or R⁶ and R⁷ are bonded together at the otherends; R⁸ is —C(O)O— (ester group), —C(O)— (keto group), or an o-, m-, orp-phenylene group; R⁹ is a direct bond or a divalent organic grouphaving 1 to 20 carbon atoms, which may contain at least one ether bond;and X is chlorine, bromine, or iodine).

Specific examples of substituents R⁶ and R⁷ include hydrogen, methyl,ethyl, n-propyl, isopropyl, butyl, pentyl, and hexyl group. SubstituentsR⁶ and R⁷ may be bonded together at the other ends to form a cyclicskeleton.

Specific examples of an alkenyl group-containing organic haliderepresented by the general formula 2 are the following:

XCH₂C(O)O(CH₂)_(n)CH═CH₂,H₃CC(H)(X)C(O)O(CH₂)_(n)CH═CH₂,(H₃C)₂C(X)C(O)O(CH₂)_(n)CH═CH₂,CH₃CH₂C(H)(X)C(O)O(CH₂)_(n)CH═CH₂, and

(wherein X is chlorine, bromine, or iodine, and n is an integer of 0 to20);XCH₂C(O)O(CH₂)_(n)O(CH₂)_(m)CH═CH₂,H₃CC(H)(X)C(O)O(CH₂)_(n)O(CH₂)_(m)CH═CH₂,(H₃C)₂C(X)C(O)O(CH₂)_(n)O(CH₂)_(m)CH═CH₂,CH₃CH₂C(H)(X)C(O)O(CH₂)_(n)O(CH₂)_(m)CH═CH₂, and

(wherein X is chlorine, bromine, or iodine, n is an integer of 0 to 20,and m is an integer of 1 to 20);o, m, p-XCH₂—C₆H₄—(CH₂)_(n)—CH═CH₂,o, m, p-CH₃C(H)(X)—C₆H₄—(CH₂)_(n)—CH═CH₂, ando, m, p-CH₃CH₂C(H)(X)—C₆H₄—(CH₂)_(n)—CH═CH₂(wherein X is chlorine, bromine, or iodine, and n is an integer of 0 to20);o, m, p-XCH₂—C₆H₄—(CH₂)_(n)—O—(CH₂)_(m)—CH═CH₂,o, m, p-CH₃C(H)(X)—C₆H₄—(CH₂)_(n)—O—(CH₂)_(m)—CH═CH₂ ando, m, p-CH₃CH₂C(H)(X)—C₆H₄—(CH₂)_(n)—O—(CH₂)_(m)CH═CH₂(wherein X is chlorine, bromine, or iodine, n is an integer of 0 to 20,and m is an integer of 1 to 20);o, m, p-XCH₂—C₆H₄—O—(CH₂)_(n)—CH═CH₂,o, m, p-CH₃C(H)(X)—C₆H₄—O—(CH₂)_(n)—CH═CH₂, ando, m, p-CH₃CH₂C(H)(X)—C₆H₄—O—(CH₂)_(n)—CH═CH₂(wherein X is chlorine, bromine, or iodine, and n is an integer of 0 to20); ando, m, p-XCH₂—C₆H₄—O—(CH₂)_(n)—O—(CH₂)_(m)—CH═CH₂,o, m, p-CH₃C(H)(X)—C₆H₄—O—(CH₂)_(n)—O—(CH₂)_(m)—CH═CH₂, ando, m, p-CH₃CH₂C(H)(X)—C₆H₄—O—(CH₂)_(n)—O—(CH₂)—CH═CH₂(wherein X is chlorine, bromine, or iodine, n is an integer of 0 to 20,and m is an integer of 1 to 20).

Other examples of an organic halide having an alkenyl group includecompounds represented by the general formula 3:

H₂C═C(R⁵)—R⁹—C(R⁶)(X)—R¹⁰—R⁷  (3)

(wherein R⁵, R⁶, R⁷, R⁹, and X represent the same as the above, and R¹⁰represents a direct bond or —C(O)O— (ester group), —C(O)— (keto group),or an o-, m-, or p-phenylene group).

R⁹ is a direct bond or a divalent organic group having 1 to 20 carbonatoms (which may contain at least one ether bond). When R⁹ is a directbond, the compound is a halogenated allyl compound in which a vinylgroup is bonded to the carbon bonded to a halogen. In this case, thecarbon-halogen bond is activated by the adjacent vinyl group, and thus aC(O)O or phenylene group is not necessarily required as R¹⁰, and adirect bond may be present. When R⁹ is not a direct bond, R¹⁰ ispreferably a C(O)O, C(O), or phenylene group for activating thecarbon-halogen bond.

Specific examples of the compounds represented by the general formula 3include the following:

CH₂═CHCH₂X, CH₂═C(CH₃)CH₂X, CH₂═CHC(H)(X)CH₃, CH₂═C(CH₃)C(H)(X)CH₃,CH₂═CHC(X)(CH₃)₂, CH₂═CHC(H)(X)C₂H₅,

CH₂═CHC(H)(X)CH(CH₃)₂, CH₂═CHC(H)(X)C₆H₅, CH₂═CHC(H)(X)CH₂C₆H₅,

CH₂═CHCH₂C(H)(X)—CO₂R¹¹, CH₂═CH(CH₂)₂C(H)(X)—CO₂R¹¹,CH₂═CH(CH₂)₃C(H)(X)—CO₂R¹¹, CH₂═CH(CH₂)₈C(H)(X)—CO₂R¹¹,CH₂═CHCH₂C(H)(X)—C₆H₅, CH₂═CH(CH₂)₂C(H)(X)—C₆H₅, andCH₂═CH(CH₂)₃C(H)(X)—C₆H₅

(wherein X is chlorine, bromine, or iodine, and R¹¹ is an alkyl, aryl,or aralkyl group having 1 to 20 carbon atoms).

Specific examples of a halogenated sulfonyl compound having an alkenylgroup include the following:

o-, m-, p-CH₂═CH—(CH₂)_(n)—C₆H₄—SO₂X, ando-, m-, p-CH₂═CH—(CH₂)_(n)—O—C₆H₄—SO₂X(wherein X is chlorine, bromine, or iodine, and n is an integer of 0 to20).

Specific examples of an organic halide having a crosslinkable silylgroup include, but not limited to, compounds with a structurerepresented by the general formula 4:

R⁶R⁷C(X)—R⁸—R⁹—C(H)(R⁵)CH₂—[Si(R¹)_(2-b)(Y)_(b)O]_(l)—Si(R²)_(3-a)(Y)_(a)  (4)

(wherein R⁵, R⁶, R⁷, R⁸, R⁹ and X represent the same as the above, andR¹ and R² are the same or different and each represents an alkyl grouphaving 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms,or an aralkyl group having 7 to 20 carbon atoms, or a triorganosiloxygroup represented by (R′)₃SiO— (the three R′s each is a monovalenthydrocarbon group having 1 to 20 carbon atoms and may be the same ordifferent); when two or more groups R¹ or R² are present, they may bethe same or different; Y represents a hydroxyl group or a hydrolyzablegroup, and when two or more groups Y are present, they may be the sameor different; a represents 0, 1, 2, or 3; b represents 0, 1, or 2; lrepresents an integer of 0 to 19; and a+lb≧1 is satisfied).

Specific examples of the compounds represented by the general formula 4include the following:

XCH₂C(O)O(CH₂)_(n)Si(OCH₃)₃,CH₃C(H)(X)C(O)O(CH₂)_(n)Si(OCH₃)₃,(CH₃)₂C(X)C(O)O(CH₂)_(n)Si(OCH₃)₃,XCH₂C(O)O(CH₂)_(n)Si(CH₃)(OCH₃)₂,

CH₃C(H)(X)C(O)O(CH₂)Si(CH₃)(OCH₃)₂, and(CH₃)₂C(X)C(O)O(CH₂)Si(CH₃)(OCH₃)₂

(wherein X is chlorine, bromine, or iodine, and n is an integer of 0 to20);XCH₂C(O)O(CH₂)_(n)O(CH₂)_(m)Si(OCH₃)₃,H₃CC(H)(X)C(O)O(CH₂)_(n)O(CH₂)_(m)Si(OCH₃)₃,(H₃C)₂C(X)C(O)O(CH₂)_(n)O(CH₂)_(m)Si(OCH₃)₃,CH₃CH₂C(H)(X)C(O)O(CH₂)_(n)O(CH₂)_(m)Si(OCH₃)₃,XCH₂C(O)O(CH₂)_(n)O(CH₂)_(m)Si (CH₃)(OCH₃)₂,H₃CC(H)(X)C(O)O(CH₂)_(n)O(CH₂)_(m)—Si(CH₃)(OCH₃)₂,(H₃C)₂C(X)C(O)O(CH₂)_(n)O(CH₂)_(m)—Si(CH₃)(OCH₃)₂, andCH₃CH₂C(H)(X)C(O)O(CH₂)_(n)(CH₂)_(m)—Si(CH₃)(OCH₃)₂,(wherein X is chlorine, bromine, or iodine, n is an integer of 0 to 20,and m is an integer of 1 to 20); ando, m, p-XCH₂—C₆H₄—(CH₂)₂Si (OCH₃)₃,o, m, p-CH₃C(H)(X)—C₆H₄—(CH₂)₂Si(OCH₃)₃,o, m, p-CH₃CH₂C(H)(X)—C₆H₄—(CH₂)₂Si(OCH₃)₃,o, m, p-XCH₂—C₆H₄—(CH₂)₃Si (OCH₃)₃,o, m, p-CH₃C(H)(X)—C₆H₄—(CH₂)₃Si(OCH₃)₃,o, m, p-CH₃CH₂C(H)(X)—C₆H₄—(CH₂)₃Si(OCH₃)₃,o, m, p-XCH₂—C₆H₄—(CH₂)₂—O—(CH₂)₃Si (OCH₃)₃,o, m, p-CH₃C(H)(X)—C₆H₄—(CH₂)₂—O—(CH₂)₃Si(OCH₃)₃,o, m, p-CH₃CH₂C(H)(X)—C₆H₄—(CH₂)₂—O—(CH₂)₃Si (OCH₃)₃,o, m, p-XCH₂—C₆H₄—O—(CH₂)₃Si (OCH₃)₃,o, m, p-CH₃C(H)(X)—C₆H₄—O—(CH₂)₃Si(OCH₃)₃,o, m, p-CH₃CH₂C(H)(X)—C₆H₄—O—(CH₂)₃—Si (OCH₃)₃,o, m, p-XCH₂—C₆H₄—O—(CH₂)₂—O—(CH₂)₃—Si (OCH₃)₃,o, m, p-CH₃C(H)(X)—C₆H₄—O—(CH₂)₂—O—(CH₂)₃Si (OCH₃)₃, ando, m, p-CH₃CH₂C(H)(X)—C₆H₄—O—(CH₂)₂—O—(CH₂)₃Si (OCH₃)₃(wherein X is chlorine, bromine, or iodine).

Other examples of the organic halide having a crosslinkable silyl groupinclude compounds with a structure represented by the general formula 5:

(R²)_(3-a)(Y)_(a)Si—[OSi(R¹)_(2-b)(Y)_(b)]_(l)—CH₂—C(H)(R⁵)—R⁹—C(R⁶)(X)—R¹⁰—R⁷  (5)

(wherein R⁵, R⁶, R⁷, R⁹, R¹⁰, R¹¹, R¹², a, b, l, X and Y represent thesame as the above; and a+lb≧1 is satisfied).

Specific examples of such compounds include the following:

(CH₃O)₃SiCH₂CH₂C(H)(X)C₆H₅, (CH₃O)₂(CH₃)SiCH₂CH₂C(H)(X)C₆H₅,(CH₃O)₃Si(CH₂)₂C(H)(X)—CO₂R¹¹, (CH₃O)₂(CH₃)Si(CH₂)₂C(H)(X)—CO₂R¹¹,(CH₃O)₃Si(CH₂)₃C(H)(X)—CO₂R¹¹, (CH₃O)₂(CH₃)Si(CH₂)₃C(H)(X)—CO₂R¹¹,(CH₃O)₃Si(CH₂)₄C(H)(X)—CO₂R¹¹, (CH₃O)₂(CH₃)Si(CH₂)₄C(H)(X)—CO₂R¹¹,(CH₃O)₃Si(CH₂)₉C(H)(X)—CO₂R¹¹, (CH₃O)₂(CH₃)Si(CH₂)₉C(H)—(X)CO₂R¹¹,(CH₃O)₃Si(CH₂)₃C(H)(X)—C₆H₅, (CH₃O)₂ (CH₃)Si(CH₂)₃C(H)(X)—C₆H₅,(CH₃O)₃Si(CH₂)₄C(H)(X)—C₆H₅, and (CH₃O)₂ (CH₃)Si(CH₂)₄C(H)(X)—C₆H₅

(wherein X is chlorine, bromine, or iodine, and R¹¹ is alkyl, aryl, oraralkyl group having 1 to 20 carbon atoms).

Examples of the hydroxyl group-containing organic halide or halogenatedsulfonyl compound include, but not limited to, the following:

HO—(CH₂)_(m)—OC(O)C(H)(R³)(X)(wherein X is chlorine, bromine, or iodine, R³ is a hydrogen atom oralkyl, aryl, or aralkyl group having 1 to 20 carbon atoms, and m is aninteger of 1 to 20).

Examples of the amino group-containing organic halide or halogenatedsulfonyl compound include, but not limited to, the following:

H₂N—(CH₂)_(m)—OC(O)C(H)(R³)(X)(wherein X is chlorine, bromine, or iodine, R³ is a hydrogen atom oralkyl, aryl, or aralkyl group having 1 to 20 carbon atoms, and m is aninteger of 1 to 20).

Examples of the epoxy group-containing organic halide or halogenatedsulfonyl compound include, but not limited to, the following:

(wherein X is chlorine, bromine, or iodine, R³ is a hydrogen atom oralkyl, aryl, or aralkyl group having 1 to 20 carbon atoms, and m is aninteger of 1 to 20).

In order to obtain a polymer having at least two polymerizationpropagation terminal structures per molecule, an organic halide orhalogenated sulfonyl compound having at least two initiation points ispreferably used as the initiator. Examples of such a compound includethe following:

(wherein C₆H₄ is a phenylene group, and X is chlorine, bromine, oriodine.)

(wherein R¹¹ is an alkyl, aryl, or aralkyl group having 1 to 20 carbonatoms, n is an integer of 0 to 20, and X is chlorine, bromine, oriodine.)

(wherein X is chlorine, bromine, or iodine, and n is an integer of 0 to20.)

(wherein m is an integer of 1 to 20, and X is chlorine, bromine, oriodine.)

(wherein X is chlorine, bromine, or iodine.)

The vinyl monomer used in the polymerization is not particularlylimited, and any of the compounds listed above can be preferably used.

The transition metal complex used as the polymerization catalyst is notparticularly limited, but a metal complex composed of a VII, VIII, IX,X, or XI group element in the periodic table as a central metal ispreferred. A complex of zero-valent copper, monovalent copper, divalentruthenium, divalent iron, or divalent nickel is more preferred. Amongthese complexes, a copper complex is most preferred. Specific examplesof a monovalent copper compound include cuprous chloride, cuprousbromide, cuprous iodide, cuprous cyanide, cuprous oxide, and cuprousperchlorate. When a copper compound is used, a ligand, such as2,2′-bipyridyl or its derivative, 1,10-phenanthroline or its derivative,or polyamine, e.g., tetramethylethylenediamine,pentamethyldiethylenetriamine, or hexamethyl tris(2-aminoethyl)amine, isadded for increasing catalyst activity. As a ligand, nitrogen-containingcompounds are preferred, chelate nitrogen compounds are more preferred,N,N,N′,N″,N″-pentamethyldiethylenetriamine is further preferred. Also, atristriphenylphosphine complex (RuCl₂(PPh₃)₃) of divalent rutheniumchloride is suitable as the catalyst. When a ruthenium compound is usedas a catalyst, an aluminum alkoxide is added as an activator.Furthermore, a bistriphenylphosphine complex (FeCl₂(PPh₃)₂) of divalentiron, a bistriphenylphosphine complex (NiCl₂(PPh₃)₂) of divalent nickel,or a bistributylphosphine complex (NiBr₂(PBu₃)₂) of divalent nickel ispreferred as the catalyst.

The polymerization can be performed without a solvent or in any ofvarious solvents. Examples of the solvent include hydrocarbon solvents,such as benzene and toluene; ether solvents, such as diethyl ether andtetrahydrofuran; halogenated hydrocarbon solvents, such as methylenechloride and chloroform; ketone solvents, such as acetone, methyl ethylketone, and methyl isobutyl ketone; alcohol solvents, such as methanol,ethanol, propanol, isopropanol, n-butyl alcohol, and tert-butyl alcohol;nitrile solvents, such as acetonitrile, propionitrile, and benzonitrile;ester solvents, such as ethyl acetate and butyl acetate; and carbonatesolvents, such as ethylene carbonate and propylene carbonate. Thesesolvents can be used alone or as a mixture of two or more.

The polymerization can be performed in a range of 0° C. to 200° C., andpreferably 50° C. to 150° C. without any purpose of restriction.

The atom transfer radical polymerization of the invention includes socalled reverse atom transfer radical polymerization. The reverse atomtransfer radical polymerization is a method comprising reacting anordinary atom transfer radical polymerization catalyst in its highoxidation state resulting from radical generation, for example Cu(II′)when Cu(I) is used as the catalyst, with an ordinary radical initiator,such as a peroxide, to thereby bring about an equilibrium state like inatom transfer radical polymerization (cf. Macromolecules, 1999, 32,2872).

<Functional Groups> Number of Crosslinkable Silyl Groups

The vinyl polymer (I) has at least one crosslinkable silyl groups. Thenumber of crosslinkable silyl groups is, from the viewpoint of thecurability of the composition and the physical properties of the curedproduct, preferably not smaller than 1.1 but not greater than 4.0, morepreferably not smaller than 1.2 but not greater than 3.5, on average.

Positions of Crosslinkable Silyl Groups

In cases where the cured products resulting from curing of the curablecomposition of the present invention are especially required to haverubber-like properties, it is preferred that at least one ofcrosslinkable silyl groups be positioned at a terminus of the molecularchain so that the molecular weight between crosslinking sites, which hasa great influence on the rubber elasticity, can be increased. Morepreferably, all crosslinkable functional groups are located at molecularchain termini.

Methods of producing vinyl polymers (I), in particular (meth)acrylicpolymers, having at least one crosslinkable silyl group such asmentioned above at a molecular terminus thereof are disclosed inJapanese Kokoku Publication Hei-03-14068, Japanese Kokoku PublicationHei-04-55444 and Japanese Kokai Publication Hei-06-211922, among others.However, these methods are free radical polymerization methods in whichthe above-mentioned “chain transfer agent methods” is used and,therefore, the polymers obtained generally have problems, namely theyshow a molecular weight distribution represented by Mw/Mn as wide as notless than 2 as well as a high viscosity, although they havecrosslinkable functional groups, in relatively high proportions, atmolecular chain termini.

Therefore, for obtaining vinyl polymers showing a narrow molecularweight distribution and a low viscosity and having crosslinkablefunctional groups, in high proportions, at molecular chain termini, theabove-described “living radical polymerization method” is preferablyused.

In the following, an explanation is made of these functional groups.

Crosslinkable Silyl Groups

As the crosslinkable silyl groups of vinyl polymers (I) to be used inthe practice of the present invention, there may be mentioned thosegroups represented by the general formula 1:

—[Si(R¹)_(2-b)(Y)_(b)O]_(l)—Si(R²)_(3-a)(Y)_(a)  (1)

{wherein, R¹ and R² are the same or different and each is an alkyl groupcontaining 1 to 20 carbon atoms, an aryl group containing 6 to 20 carbonatoms, an aralkyl group containing 7 to 20 carbon atoms or atriorganosiloxy group represented by (R′)₃SiO— (in which R′ is aunivalent hydrocarbon group containing 1 to 20 carbon atoms and thethree R′ groups may be the same or different) and, when there are two ormore R¹ or R² groups, they may be the same or different; Y represents ahydroxyl group or a hydrolyzable group and, when there are two or more Ygroups, they may be the same or different; a represents 0, 1, 2 or 3, brepresents 0, 1 or 2, and l is an integer of 0 to 19, provided that therelation a+lb≧1 should be satisfied.}

As the hydrolyzable group, there may be mentioned, among others, ahydrogen atom and those groups which are in general use, for examplealkoxy, acyloxy, ketoximate, amino, amido, aminoxy, mercapto andalkenyloxy groups. Among them, alkoxy, amido and aminoxy groups arepreferred. In view of mild hydrolyzability and ease of handling, alkoxygroups are particularly preferred.

One to three hydrolyzable groups and/or hydroxyl groups can be bound toeach silicon atom and it is preferred that (a+Σb) be within the range of1 to 5. When there are two or more hydrolyzable groups or hydroxylgroups in one crosslinkable silyl group, they may be the same ordifferent. The number of silicon atoms forming the crosslinkable silylgroup is not less than 1 and, in the case of silicon atoms connected bysiloxane or like bonding, it is preferably not more than 20.Particularly preferred are crosslinkable silyl groups represented by thegeneral formula 7:

—Si(R²)_(3-a)(Y)_(a)  (7)

(wherein R² and Y are as defined above; and a represents 1, 2 or 3)because of ready availability.

Considering the curability, the integer a is preferably 2 or more,though this is not critical. One in which a is 3 (e.g. trimethoxyfunctional group) is faster in curability than one in which a is 2 (e.g.dimethoxy functional group) but, as for the storage stability and/ormechanical properties (e.g. elongation), one in which a is 2 issometimes superior. For attaining a balance between curability andphysical properties, one in which a is 2 (e.g. dimethoxy functionalgroup) and one in which a is 3 (e.g. trimethoxy functional group) may beused in combination.

<Silyl Group Introduction Method>

In the following, several methods of silyl group introduction into thevinyl polymer (I) of the present invention are described without anypurpose of restriction.

As methods of synthesizing vinyl polymers (I) having at least onecrosslinkable silyl group, there may be mentioned, among others,

(A) the method which comprises subjecting a crosslinkable silylgroup-containing hydrosilane compound to addition to a vinyl polymerhaving at least one alkenyl group in the presence of a hydrosilylationcatalyst,

(B) the method which comprises reacting a vinyl polymer having at leastone hydroxyl group with a compound having, in each molecule, acrosslinkable silyl group and a group capable of reacting with thehydroxyl group, such as an isocyanato group,

(C) the method which comprises subjecting a compound having, in eachmolecule, a polymerizable alkenyl group and a crosslinkable silyl groupto reaction in synthesizing a vinyl polymer by radical polymerization,

(D) the method which comprises subjecting a chain transfer agent havinga crosslinkable silyl group to reaction in synthesizing a vinyl polymerby radical polymerization, and

(E) the method which comprises reacting a vinyl polymer having at leastone highly reactive carbon-halogen bond with a compound having, in eachmolecule, a crosslinkable silyl group and a stable carbanion.

The vinyl polymer having at least one alkenyl group, which is to be usedin the above method (A), can be obtained by various methods. Severalmethods of synthesis are mentioned below, without any purpose ofrestriction, however.

(A-a) Method comprising subjecting to reaction a compound having, ineach molecule, a polymerizable alkenyl group together with a lowpolymerizability alkenyl group, such as one represented by the generalformula 8 shown below as a second monomer in synthesizing a vinylpolymer by radical polymerization:

H₂C═C(R¹⁴)—R¹⁵—R¹⁶—C(R¹⁷)═CH₂  (8)

(wherein R¹⁴ represents a hydrogen atom or a methyl group, R¹⁵represents —C(O)O— or an o-, m- or p-phenylene group, R¹⁶ represents adirect bond or a divalent organic group containing 1 to 20 carbon atoms,which may contain one or more ether bonds, and R¹⁷ represents a hydrogenatom, an alkyl group containing 1 to 20 carbon atoms, an aryl groupcontaining 6 to 20 carbon atoms or an aralkyl group containing 7 to 20carbon atoms).

The time when the compound having, in each molecule, a polymerizablealkenyl group together with a low polymerizability alkenyl group issubjected to reaction is not particularly restricted but, in particularin living radical polymerization and when rubber-like properties areexpected, the compound is preferably subjected to reaction as a secondmonomer at the final stage of the polymerization reaction or aftercompletion of the reaction of the employed monomers.

(A-b) Method comprising subjecting to reaction a compound having atleast two low polymerizability alkenyl groups, for example1,5-hexadiene, 1,7-octadiene or 1,9-decadiene, at the final stage of thepolymerization or after completion of the reaction of the monomersemployed in vinyl polymer synthesis by living radical polymerization.

(A-c) Method comprising reacting a vinyl polymer having at least onehighly reactive carbon-halogen bond with one of variousalkenyl-containing organometallic compounds, for example an organotinsuch as allyltributyltin or allyltrioctyltin, for substitution of thehalogen.

(A-d) Method comprising reacting a vinyl polymer having at least onehighly reactive carbon-halogen bond with a stabilized,alkenyl-containing carbanion such as one represented by the generalformula 9, for substitution of the halogen:

M⁺C⁻(R¹⁸)(R¹⁹)—R²⁰—C(R¹⁷)═CH₂  (9)

(wherein R¹⁷ is as defined above, R¹⁸ and R¹⁹ each is anelectron-withdrawing group capable of stabilizing the carbanion C⁻ orone of them is such an electron-withdrawing group and the otherrepresents a hydrogen atom, an alkyl group containing 1 to 10 carbonatoms or a phenyl group, R²⁰ represents a direct bond or a divalentorganic group containing 1 to 10 carbon atoms, which may contain one ormore ether bonds, and M⁺ represents an alkali metal ion or a quaternaryammonium ion).

Particularly preferred as the electron-withdrawing group R¹⁸ and/or R¹⁹are those which have a structure of —CO₂R, —C(O)R or —CN.

(A-e) Method comprising reacting a vinyl polymer having at least onehighly reactive carbon-halogen bond with a simple substance metal, suchas zinc, or an organometallic compound and then reacting thethus-prepared enolate anion with an alkenyl-containing, electrophiliccompound, such as an alkenyl-containing compound having a leaving groupsuch as a halogen atom or an acetyl group, an alkenyl-containingcarbonyl compound, an alkenyl-containing isocyanate compound or analkenyl-containing acid halide.

(A-f) Method comprising reacting a vinyl polymer having at least onehighly reactive carbon-halogen bond with an alkenyl-containing oxy anionor carboxylate anion such as one represented by the general formula (10)or (11), for substitution of the halogen:

H₂C═C(R¹⁷)—R²¹—O⁻M⁺  (10)

(wherein R¹⁷ and M⁺ are as defined above and R²¹ is a divalent organicgroup containing 1 to 20 carbon atoms, which may contain one or moreether bonds);

H₂C═C(R¹⁷)—R²²—C(O)O⁻M⁺  (11)

(wherein R¹⁷ and M⁺ are as defined above and R²² is a direct bond or adivalent organic group containing 1 to 20 carbon atoms, which maycontain one or more ether bonds).

The method of synthesizing the above-mentioned vinyl polymer having atleast one highly reactive carbon-halogen bond includes, but is notlimited to, atom transfer radical polymerization methods using anorganic halide or the like as initiator and a transition metal complexas catalyst, as mentioned above.

It is also possible to obtain the vinyl polymer having at least onealkenyl group from a vinyl polymer having at least one hydroxyl group.As utilizable methods, there may be mentioned, for example, thefollowing, without any purpose of restriction.

(A-g) Method comprising reacting the hydroxyl group of a vinyl polymerhaving at least one hydroxyl group with a base, such as sodiummethoxide, followed by reaction with an alkenyl-containing halide, suchas allyl chloride.

(A-h) Method comprising reacting such hydroxyl group with analkenyl-containing isocyanate compound, such as allyl isocyanate.

(A-i) Method comprising reacting such hydroxyl group with analkenyl-containing acid halide, such as (meth)acrylic acid chloride, inthe presence of a base, such as pyridine.

(A-j) Method comprising reacting such hydroxyl group with analkenyl-containing carboxylic acid, such as acrylic acid, in thepresence of an acid catalyst.

In the practice of the present invention, when no halogen is directlyinvolved in the alkenyl group introduction, as in the method (A-a) or(A-b), the vinyl polymer is preferably synthesized by living radicalpolymerization. From the viewpoint of ready controllability, the method(A-b) is more preferred.

In cases where alkenyl group introduction is effected by conversion ofthe halogen atom of a vinyl polymer having at least one highly reactivecarbon-halogen atom, use is preferably made of a vinyl polymer having atleast one terminal carbon-halogen bond, which is highly reactive, asobtained by subjecting a vinyl monomer to radical polymerization (atomtransfer radical polymerization) using, as an initiator, an organichalide or halogenated sulfonyl compound having at least one highlyreactive carbon-halogen bond and, as a catalyst, a transition metalcomplex. In view of easier controllability, the method (A-f) is morepreferred.

The crosslinkable silyl group-containing hydrosilane compound is notparticularly restricted but includes, as typical examples, compoundsrepresented by the general formula 12.

H—[Si (R¹)_(2-b)(Y)_(b)O]_(l)—Si(R²)_(3-a)(Y)_(a)  (12)

{wherein R¹ and R² are the same or different and each represents analkyl group containing 1 to 20 carbon atoms, an aryl group containing 6to 20 carbon atoms, an aralkyl group containing 7 to 20 carbon atoms ora triorganosiloxy group represented by (R′)₃SiO— (in which R′ is aunivalent hydrocarbon group containing 1 to 20 carbon atoms and thethree R′ groups may be the same or different) and, when there are two ormore R¹ or R² groups, they may be the same or different; Y represents ahydroxyl group or a hydrolyzable group and, when there are two or more Ygroups, they may be the same or different; a represents 0, 1, 2 or 3, brepresents 0, 1 or 2 and l is an integer of 0 to 19, provided that therelation a+lb≧1 should be satisfied}.

Particularly preferred among those hydrosilane compounds in view ofready availability are crosslinkable group-containing compoundsrepresented by the general formula 13:

H—Si(R²)_(3-a)(Y)_(a)  (13)

(wherein R² and Y are as defined above; and a represents 1, 2 or 3).

In subjecting the above crosslinkable silyl-containing hydrosilanecompound to addition to the alkenyl group, a transition metal catalystis generally used. The transition metal catalyst includes, among others,simple substance platinum; solid platinum dispersed on a support such asalumina, silica or carbon black; chloroplatinic acid; chloroplatinicacid complexes with alcohols, aldehydes, ketones or the like;platinum-olefin complexes; and platinum(0)-divinyltetramethyldisiloxanecomplex. As other catalysts than platinum compounds, there may bementioned RhCl(PPh₃)₃, RhCl₃, RuCl₃, IrCl₃, FeCl₃, AlCl₃, PdCl₂.H₂O,NiCl₂ and TiCl₄, for instance.

The method of producing the vinyl polymer having at least one hydroxylgroup, which polymer is to be used in the methods (B) and (A-g) to(A-j), includes, but is not limited to, the following, among others.

(B-a) Method comprising subjecting to reaction, as a second monomer, acompound having both a polymerizable alkenyl group and a hydroxyl groupin each molecule, for example one represented by the general formula 14given below, in synthesizing the vinyl polymer by radicalpolymerization:

H₂C═C(R¹⁴)—R¹⁵—R¹⁶—OH  (14)

(wherein R¹⁴, R¹⁵ and R¹⁶ are as defined above).

The time for subjecting to reaction the compound having both apolymerizable alkenyl group and a hydroxyl group in each molecule is notcritical but, in particular in living radical polymerization, whenrubber-like properties are demanded, the compound is preferablysubjected to reaction as a second monomer at the final stage of thepolymerization reaction or after completion of the reaction of theemployed monomer.

(B-b) Method comprising subjecting an alkenyl alcohol, such as10-undecenol, 5-hexenol or allyl alcohol, to reaction at the final stageof polymerization reaction or after completion of the reaction of theemployed monomer in synthesizing the vinyl polymer by living radicalpolymerization.

(B-c) Method comprising radical-polymerizing a vinyl monomer using ahydroxyl-containing chain transfer agent, such as a hydroxyl-containingpolysulfide, in large amounts, as described in Japanese KokaiPublication Hei-05-262808, for instance.

(B-d) Method comprising subjecting a vinyl monomer to radicalpolymerization using hydrogen peroxide or a hydroxyl-containinginitiator, as described in Japanese Kokai Publication Hei-06-239912 andJapanese Kokai Publication Hei-08-283310, for instance.

(B-e) Method comprising subjecting a vinyl monomer to radicalpolymerization using an alcohol in excess, as described in JapaneseKokai Publication Hei-06-116312, for instance.

(B-f) Method comprising introducing a terminal hydroxyl group byhydrolyzing the halogen atom of a vinyl polymer having at least onehighly reactive carbon-halogen bond or reacting such halogen atom with ahydroxyl-containing compound, according to the method described inJapanese Kokai Publication Hei-04-132706, for instance.

(B-g) Method comprising reacting a vinyl polymer having at least onehighly reactive carbon-halogen bond with a hydroxyl-containingstabilized carbanion, such as one represented by the general formula 15for substitution of the halogen atom:

M⁺C⁻(R¹⁸)(R¹⁹)—R²⁰—OH  (15)

(wherein R¹⁸, R¹⁹ and R²⁰ are as defined above).

Particularly preferred as the electron-withdrawing groups R¹⁸ and R¹⁹are those having a structure of —CO₂R, —C(O)R or —CN.

(B-h) Method comprising reacting a vinyl polymer having at least onehighly reactive carbon-halogen bond with a simple substance metal, suchas zinc, or an organometallic compound and then reacting thethus-prepared enolate anion with an aldehyde or ketone.

(B-i) Method comprising reacting a vinyl polymer having at least onehighly reactive carbon-halogen bond with a hydroxyl-containing oxy anionor carboxylate anion, such as one represented by the general formula 16or 17 given below, for substitution of the halogen atom:

HO—R²¹—O⁻M⁺  (16)

(wherein R²¹ and M⁺ are as defined above);

HO—R²²—C(O)O⁻M⁺  (17)

(wherein R²² and M⁺ are as defined above).

(B-j) Method comprising subjecting, as a second monomer, a compoundhaving a low polymerizable alkenyl group and a hydroxyl group in eachmolecule to reaction at the final stage of the polymerization reactionor after completion of the reaction of the employed monomer insynthesizing the vinyl polymer by living radical polymerization.

Such compound is not particularly restricted but may be a compoundrepresented by the general formula 18, for instance:

H₂C═C(R¹⁴)—(R²¹)—OH  (18)

(wherein R¹⁴ and R²¹ are as defined above).

The compound represented by the above general formula 18 is notparticularly restricted but, in view of ready availability, alkenylalcohols such as 10-undecenol, 5-hexenol and allyl alcohol arepreferred.

In the practice of the present invention, when no halogen is directlyinvolved in hydroxyl group introduction, as in the methods (B-a) to(B-e) and (B-j), the vinyl polymer is preferably synthesized by livingradical polymerization. The method (B-b) is more preferred from theviewpoint of ease of control.

In cases where hydroxyl group introduction is effected by conversion ofthe halogen atom of a vinyl polymer having at least one highly reactivecarbon-halogen atom, use is preferably made of a vinyl polymer having atleast one terminal carbon-halogen bond, which is highly reactive, asobtained by subjecting a vinyl monomer to radical polymerization (atomtransfer radical polymerization) using an organic halide or halogenatedsulfonyl compound as an initiator and, as a catalyst, a transition metalcomplex. From the viewpoint of ease of control, the method (B-i) is morepreferred.

As the compound having a crosslinkable silyl group and a group capableof reacting with a hydroxyl group, such as an isocyanato group, in eachmolecule, there may be mentioned, for example,γ-isocyanatopropyltrimethoxysilane,γ-isocyanatopropylmethyldimethoxysialne,γ-isocyanatopropyltriethoxysilane and the like. If necessary, any ofurethane formation reaction catalysts generally known in the art can beused.

The compound having both a polymerizable alkenyl group and acrosslinkable silyl group in each molecule, which is to be used in themethod (C), includes, among others,γ-trimethoxysilylpropyl(meth)acrylate,γ-methyldimethoxysilylpropyl(meth)acrylate and like compoundsrepresented by the general formula 19 given below:

H₂C═C(R¹⁴)—R¹⁵—R²³—[Si(R¹)_(2-b)(Y)_(b)O]_(l)—Si(R²)_(3-a)(Y)_(a)  (19)

(wherein R¹, R², R¹⁴, R¹⁵, Y, a, b and l are as defined above and R²³ isa direct bond or a divalent organic group containing 1 to 20 carbonatoms, which may contain one or more ether bonds, provided that therelation a+lb≧1 should be satisfied).

The time for subjecting the compound having both a polymerizable alkenylgroup and a crosslinkable silyl group in each molecule is not criticalbut, in particular in living radical polymerization and when rubber-likeproperties are demanded, the compound is preferably subjected toreaction as a second monomer at the final stage of the polymerizationreaction or after completion of the reaction of the employed monomer.

The chain transfer agent having a crosslinkable silyl group, which is tobe used in the chain transfer agent method (D), includes mercaptanhaving a crosslinkable silyl group, hydrosilane having a crosslinkablesilyl group, and the like, described in Japanese Kokoku PublicationHei-03-14068, Japanese Kokoku Publication Hei-04-55444, for instance.

The method of synthesizing the vinyl polymer having at least one highlyreactive carbon-halogen bond, which is to be used in the method (E),includes, but is not limited to, the atom transfer radicalpolymerization method which uses an organic halide or the like as aninitiator and a transition metal complex as a catalyst.

As the compound having both a crosslinkable silyl group and a stabilizedcarbanion in each molecule, there may be mentioned compounds representedby the general formula 2:

M⁺C⁻(R¹⁸)(R¹⁹)—R²⁴—C(H)(R²⁵)—CH₂—[Si(R¹)_(2-b)(Y)_(b)O]_(l)—Si(R²)_(3-a)(Y)_(a)  (20)

(wherein R¹, R², R¹⁸, R¹⁹, Y, a, b, l and M⁺ are as defined above, R²⁴is a direct bond or a divalent organic group containing 1 to 10 carbonatoms, which may contain one or more ether bonds, and R²⁵ represents ahydrogen atom, an alkyl group containing 1 to 10 carbon atoms, an arylgroup containing 6 to 10 carbon atoms or an aralkyl group containing 7to 10 carbon atoms, provided that the relation a+lb≧1 should besatisfied).

Particularly preferred as the electron-withdrawing groups R¹⁸ and R¹⁹are those having a structure of —CO₂R, —C(O) or —CN.

<<Micronized Hydrophobic Silica (II)>>

The micronized hydrophobic silica (II) of the invention may bemicronized silica such as fumed silica (fume-like silica).

The micronized silica is a highly dispersible white silicon dioxideconsisting of spherical primary particles produced from a volatilesilane compound using high temperature flame hydrolysis method. Theprimary particles do not exist separately but form agglomerates or bulkparticles. These particles have siloxane or silanol groups on thesurface.

The micronized hydrophobic silica (II) of the invention is the onechemically surface-treated by reaction of the silanol groups withsilanes, silazanes and the like. Preferable examples are those which aretreated with organosilicon compound such as dimethyldichlorosilane,hexamethyldisilazane, dimethylsiloxane, trimethoxyoctylsilane, anddimethylsilicone to exhibit hydrophobicity. The treatment for making thesurface hydrophobic causes an effect to suppress water absorption andmake the micronized silica easy to be dispersed in the vinyl polymer (I)produced by the living radical polymerization.

Examples of available commercial products of the micronized hydrophobicsilica (II) are Aerosil manufactured by Nippon Aerosil Co., Ltd.,Sylophobic manufactured by FUJI SILYSIA CHEMICAL LTD., and the like.

The particle diameter of the micronized hydrophobic silica (II) is notparticularly limited and smaller diameter is preferable, however. It isbecause if the particle diameter of the micronized hydrophobic silica(II) is smaller than the wavelength of visible light rays, transparencyseems to be obtained when the micronized hydrophobic silica (II) isdispersed in the curable composition of the invention.

Practically, the preferred micronized silica is an ultrafine-micronizedsilica which has a specific surface area (measured by BET adsorptionmethod) of preferably 50 m²/g or higher, more preferably about 50 to 400m²/g, and further preferably about 100 to 300 m²/g. The BET adsorptionmethod is a method which makes an inert gas molecule, having knownadsorption occupying surface area, to be physically adsorbed onto thepowder particle surface at a liquefied nitrogen temperature in order todetermine the specific surface area of the specimen from the amount ofadsorption.

In conversion of the specific surface area into the particle diameter,about 50 m²/g specific surface area is equivalent to 20 nm=0.02 μm.Accordingly the particle diameter of the micronized hydrophobic silica(II) is preferably 0.02 μm or smaller.

The addition amount of the micronized hydrophobic silica (II) ispreferably 1 to 200 parts by weight, and particularly preferably 3 to100 parts by weight, per 100 parts by weight of the vinyl polymer (I)containing a crosslinkable silyl group. If the addition amount of themicronized hydrophobic silica (II) is small and lower than 1 part byweight, the reinforcing effect and thixotropy providing effect onto thecured product tend to be difficult to be exhibited. On the other hand,if the addition amount exceeds 200 parts by weight, the viscosity of thecurable composition tends to be high before curing and therefore highpower is required on extruding the curable composition out of acartridge, which tends to result in decrease of the workability.

<<Graft Copolymer (III) Obtained by Graft Polymerization of aCrosslinkable Rubber-Like Acrylic Ester Polymer and a Vinyl Monomer>>

The graft copolymer, which is the component (III) of the invention andobtained by graft polymerization of a crosslinkable rubber-like acrylicester polymer and a vinyl monomer, is a core-shell type graft copolymercontaining a rubber-like polymer [A] with a glass transition temperatureof 0° C. or lower as a core layer and a polymer [B] as a shell layer(hereinafter, referred to as graft copolymer (III) for short).

The rubber-like polymer [A] constituting the core layer of the graftcopolymer (III) described above may have a single layer structure or amultilayer structure comprising two or more layers. Similarly, thepolymer [B] constituting the shell layer may have a single layerstructure or a multilayer structure comprising two or more layers.

Generally, graft copolymers (III) are obtained by graft copolymerizationof the rubber-like polymer [A] and a monomer mixture (b) and, in mostcases, they are obtained by graft polymerization of a monomer mixture(b) in the presence of a rubber latex [A′] containing the rubber-likepolymer [A] as a solid matter.

The monomer mixture (b) consequently gives the polymer [B] by graftpolymerization.

The rubber-like polymer [A] is a polymer obtained by polymerization of amonomer mixture (a) containing a monomer (a-1) (butadiene and/or anacrylic alkyl ester); an aromatic vinyl monomer (a-2); a vinyl monomer(a-3) copolymerizable with the monomer (a-1) (butadiene and/or anacrylic alkyl ester) and the aromatic vinyl monomer (a-2) [hereinafter,the vinyl monomer (a-3) being referred to as a copolymerizable vinylmonomer (a-3)]; and a polyfunctional monomer (a-4).

By polymerizing the above-mentioned monomer mixture (a), using emulsionpolymerization for example, a rubber latex [A′] containing rubber-likepolymer [A] can be obtained. In the case where the rubber-like polymer[A] is obtained by emulsion polymerization, the rubber-like polymer [A′]can be used as such, in the form of the rubber latex [A′] dispersed inan aqueous medium, for the graft copolymerization with the monomermixture (b). The monomer (a-1) (butadiene and/or an acrylic alkyl ester)is a component for improving the weather resistance.

Butadiene to be used for the monomer (a-1) (butadiene and/or an acrylicalkyl ester) is usually 1,3-butadiene. As typical examples of theacrylic alkyl ester, there may be mentioned, for example, acrylic alkylesters having an alkyl group of 1 to 8 carbon atoms, that is, methylacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and thelike, without any purpose of restriction. The butadiene and/or acrylicalkyl ester may be used respectively alone or as a mixture of two ormore of them.

To sufficiently improve the impact resistance of the molded article tobe finally obtained, the use amount of the monomer (a-1) (butadieneand/or an acrylic alkyl ester) is 50 to 100% by weight per the totalamount of the polymer components for obtaining the rubber-like polymer[A].

The ratio of butadiene and acrylic alkyl ester contained in the monomer(a-1) (butadiene and/or an acrylic alkyl ester) is not particularlylimited and, to give high weather resistance to the curable compositionto be finally obtained, the ratio is preferably 0 to 25% by weight ofbutadiene and 75 to 100% by weight of acrylic alkyl ester, morepreferably 0 to 12% by weight of butadiene and 88 to 100% by weight ofacrylic alkyl ester, and most preferably 0% by weight of butadiene and100% by weight of acrylic alkyl ester, per 100% by weight of the totalof butadiene and acrylic alkyl ester.

The above-mentioned aromatic vinyl monomer (a-2) is a component having afunction of improving the transparency of the cured product to befinally obtained from the vinyl polymer (I) of the invention and thus isused for adjusting the difference between the refractive index of thegraft copolymer (III) and the one of the vinyl polymer (I) as narrow aspossible.

As typical examples of the aromatic vinyl monomer (a-2), there may bementioned, for example, styrene, α-methylstyrene, 1-vinylnaphthalene,2-vinylnaphthalene, without any purpose of restriction. These aromaticvinyl monomers may be used alone or two or more of them may be used as amixture.

The use amount of the aromatic vinyl monomer (a-2) is most preferably 0to 50% by weight per the total amount of the polymerization componentsin the case of obtaining the rubber-like polymer [A] in order to avoidthe situation where the desired rubber-like polymer [A] is difficult tobe obtained due to the relatively decreased use amount of the monomer(a-1) (butadiene and/or an acrylic alkyl ester).

The copolymerizable vinyl monomer (a-3) is a component to be used forfine adjustment of the compatibility of the graft copolymer (III) andthe vinyl polymer (I).

As typical examples of the copolymerizable vinyl monomer (a-3), theremay be mentioned, for example, cyano vinyl monomers such asacrylonitrile and methacrylonitrile, 4-hydroxybutyl acrylate, withoutany purpose of restriction. These vinyl monomers may be used alone ortwo or more of them are used as a mixture.

The use amount of the copolymerizable vinyl monomer (a-3) is 0 to 20% byweight, preferably 0 to 10% by weight, and more preferably 0% by weightper the total amount of the polymerization components in the case ofobtaining the rubber-like polymer [A] in order to avoid the situationwhere the desired rubber-like polymer [A] is difficult to be obtaineddue to the relatively decreased use amount of the monomer (a-1)(butadiene and/or an acrylic alkyl ester).

The polyfunctional monomer (a-4) is a component for forming acrosslinked structure in the rubber-like polymer [A] to be obtained.

As typical examples of the polyfunctional monomer (a-4), there may bementioned, for example, divinylbenzene, allyl acrylate, allylmethacrylate, without any purpose of restriction. Further, so-calledmacromer, which is a molecule having radical polymerizable functionalgroups at both termini, e.g. α,ω-dimethacryloxypolyoxyethylene, is alsousable for the polyfunctional monomer (a-4). These polyfunctionalmonomers may be used alone or two or more of them may be used as amixture.

The use amount of the polyfunctional monomer (a-4) is 0 to 5% by weightand preferably 0.1 to 3% by weight per the total amount of thepolymerization components in the case of obtaining the rubber-likepolymer [A] in order to avoid the situation where the desiredrubber-like polymer [A] is difficult to be obtained due to therelatively decreased use amount of the monomer (a-1) (butadiene and/oran acrylic alkyl ester).

A method of obtaining the rubber-like polymer [A] is not particularlylimited and, for example, a method involving adding an aqueous medium, apolymerization initiator, an emulsifier and the like to the monomermixture (a) containing respectively desired amounts of the monomer (a-1)(butadiene and/or an acrylic alkyl ester), the aromatic vinyl monomer(a-2), the copolymerizable vinyl monomer (a-3), and the polyfunctionalmonomer (a-4), and then polymerizing the resulting mixture by a normalemulsion polymerization method etc. in order to obtain the polymer [A]contained in the rubber latex [A′].

The aqueous medium is a liquid which contains not less than 90% byweight of water and the composition of which makes the emulsionpolymerization practically possible therein. The aqueous medium maycontain 10% by weight or less of a liquid other than water and mixablewith water as long as emulsification polymerization in the aqueousmedium is possible. As examples of the liquid other than water andmixable with water, there may be mentioned acetone, methyl alcohol,ethyl alcohol, propyl alcohol, butyl alcohol, tetrahydrofuran,dimethylformaldehyde and the like, without any purpose of restriction.

As examples of the polymerization initiator, there may be mentionedorganic peroxides, e.g. peroxides of ketones or aldehydes such ascyclohexanone peroxide; diacyl peroxide such as acetyl peroxide;hydroperoxides such as tert-butyl hydroperoxide and cumenehydroperoxide; dialkyl peroxides such as di-tert-butyl peroxide; alkylesters such as tert-butyl perisobutylate; and percarbonates such astert-butyl peroxyisopropyl carbonate; inorganic peroxides such ashydrogen peroxide and potassium persulfate; and azo compounds such as2,2′-azobisisobutyronitrile; and the like, without any purpose ofrestriction. In the case where the organic peroxides and/or inorganicperoxides are used among them, they may be used as a thermaldecomposition type polymerization initiator or as a redox typepolymerization initiator by combinedly using a reducing agent such assodium ascorbate and sodium formaldehydesulfoxylate and, if necessary, apromoter such as ferrous sulfate and a chelating agent such asethylenediamine tetraacetate.

Examples of the emulsifier are surfactants and the like. The types ofthe surfactants are not particularly limited and may include anionicsurfactants, nonionic surfactants, cationic surfactants, combinations ofan anionic surfactant and a nonionic surfactant, and combinations of acationic surfactant and a nonionic surfactant. Examples of the anionicsurfactants are not particularly limited and may include alkali metalsalts of a fatty acid, such as potassium palmitate, sodium oleate, andsodium stearate; alkali metal salts or amine or ammonium salts of ahigher alcohol sulfuric acid ester, such as sodium dodecyl sulfate,triethanol amine dodecyl sulfate, and ammonium dodecyl sulfate; alkalimetal salts of an alkylbenzenesulfonic acid or alkylnaphthalenesulfonicacid, such as sodium dodecylbenzenesulfonate, and sodiumdodecylnaphthalenesulfonate; alkali metal salts, such as a sodium salt,of a naphthalenesulfonic acid formalin condensate; alkali metal salts,such as a sodium salt, of a dialkylsulfosuccinic acid; alkylphosphatesalts such as alkyl phosphoric acid salts; and polyoxyethylene sulfatessuch as sodium polyoxyethylene alkyl ether sulfate, and sodiumpolyoxyethylene alkylphenyl ether sulfate. Examples of the nonionicsurfactants are not particularly limited and may include polyoxyethylenealkyl ethers such as polyoxyethylene dodecyl ether and polyoxyethylenestearyl ether; polyoxyethylene alkylphenol ethers such aspolyoxyethylene nonylphenol ether; sorbitan fatty acid esters such assorbitan monostearate, sorbitan distearate, and sorbitan sesquioleate;polyoxyethylene sorbitan fatty acid esters such as polyoxyethylenesorbitan monostearate; polyoxyethylene acyl esters such as polyethyleneglycol monostearate and polyethylene glycol distearate;oxyethylene-oxypropylene block polymer (molecular weight of about 2,000to about 10,000); and fatty acid monoglycerides such as glycerylmonooleate. Further, the cationic surfactants are not particularlylimited and may include alkylamines such as dodecylamine acetate;quaternary ammonium salts such as dodecyltrimethylammonium chloride; andpolyoxyethylene alkylamines. In addition to them, polymer surfactantsmay be used.

The addition and polymerization of the monomer mixture (a) at the timeof obtaining the rubber-like polymer [A] may be carried out in one stageor in multi-stages, without any purpose of particular restriction. Theaddition of the monomer mixture (a) may be batch-wise or continuous, orin two- or more-steps each of these steps being carried out in acombination of the above-mentioned two methods, without any purpose ofparticular restriction.

The reaction temperature is preferably 20 to 90° C., more preferably 30to 70° C., and further preferably 40 to 60° C.

The monomer mixture (a) may be obtained by the above-mentioned method ofpreviously mixing the respectively desired amounts of the monomer (a-1)(butadiene and/or an acrylic alkyl ester), the aromatic vinyl monomer(a-2), the copolymerizable vinyl monomer (a-3), and the polyfunctionalmonomer (a-4), and also by a method of separately adding therespectively desired amounts of the monomer (a-1) (butadiene and/or anacrylic alkylester), the aromatic vinyl monomer (a-2), thecopolymerizable vinyl monomer (a-3), and the polyfunctional monomer(a-4) to a reactor previously fed with the aqueous medium, theinitiator, the emulsifier and the like, or adding a combination of someof them, and stirring and blending the mixture in the reactor in orderto obtain the final product as a micelle. In this case, by shifting thecontent of the reactor to the condition where polymerization can bestarted, polymerization of the monomer mixture (a) may be carried out bya normal emulsion polymerization method etc. in order to obtain therubber-like polymer [A] contained in the rubber latex [A′].

The glass transition temperature of the rubber-like polymer [A] obtainedin the above manner is controlled to be 0° C. or lower to make themolded article to be finally obtained sufficiently deformable even inthe case where high deformation rate is applied thereto.

The monomer mixture (b) contains a methacrylic alkyl ester monomer(b-1); an acrylic alkyl ester monomer (b-2); an aromatic vinyl monomer(b-3); a cyano vinyl monomer (b-4); and a vinyl monomer (b-5)copolymerizable with the methacrylic alkyl ester monomer (b-1), theacrylic alkyl ester monomer (b-2), the aromatic vinyl monomer (b-3), andthe cyano vinyl monomer (b-4) [hereinafter, the vinyl monomer (b-5)being referred to as a copolymerizable vinyl monomer (b-5)].

The methacrylic alkyl ester monomer (b-1) is a component to be used forimproving the adhesiveness of the graft copolymer (III) and the vinylpolymer (I) and thereby improving the strength of the cured product tobe finally obtained from the curable composition of the invention.

As typical examples of the methacrylic alkyl ester monomer (b-1), theremay be mentioned, for example, methacrylic alkyl esters having an alkylgroup of 1 to 5 carbon atoms, that is, methyl methacrylate, ethylmethacrylate, butyl methacrylate and the like, without any purpose ofrestriction. These methacrylic alkyl esters may be used alone or as amixture of two or more of them.

The use amount of the methacrylic alkyl ester monomer (b-1) is 10 to100% by weight per the total amount of the monomer mixture (b).

Use of methyl methacrylate for the methacrylic alkyl ester monomer (b-1)in an amount of preferably 60 to 100% by weight and more preferably 80to 100% by weight provides the curable composition to be finallyobtained with particularly desirable strength.

The acrylic alkyl ester monomer (b-2) is a component which adjusts thesoftening temperature of the shell layer of the graft copolymer (III) inorder to promote dispersion of the graft copolymer in the vinyl polymer(I) in the finally obtained curable composition, and thereby providesthe cured product to be finally obtained with desirable strength.

As typical examples of the acrylic alkyl ester monomer (b-2), there maybe mentioned, for example, acrylic alkyl esters having an alkyl group of2 to 12 carbon atoms, that is, ethyl acrylate, butyl acrylate,2-ethylhexyl acrylate, and the like, without any purpose of restriction.These acrylic alkyl esters may be used alone or as a mixture of two ormore of them.

The use amount of the acrylic alkyl ester monomer (b-2) is 0 to 60% byweight per the total amount of the monomer mixture (b).

In order to sufficiently keep the adhesiveness between the graftcopolymer (III) and the vinyl polymer (I), and simultaneously in a goodbalance, to give good dispersion of the graft copolymer in the vinylpolymer (I) in the cured product to be finally obtained, the ratios ofthe methacrylic alkyl ester monomer (b-1) and the acrylic alkyl estermonomer (b-2) are preferably 60 to 100% by weight of the methacrylicalkyl ester monomer (b-1) and 0 to 40% by weight of the acrylic alkylester monomer (b-2) per 100% by weight of the total of the methacrylicalkyl ester monomer (b-1) and acrylic alkyl ester monomer (b-2)contained in the monomer mixture (b).

The aromatic vinyl monomer (b-3) is a component to be used for improvingthe transparency of the cured product to be finally obtained andadjusting the difference between the refractive index of the graftcopolymer (III) and the one of the vinyl polymer (I) to be used asnarrow as possible.

As typical examples of the aromatic vinyl monomer (b-3), there may bementioned, for example, monomers exemplified as the typical examples ofthe aromatic vinyl monomer (a-2), without any purpose of restriction.The aromatic vinyl monomers may be used alone or two or more of them maybe used as a mixture.

The use amount of the aromatic vinyl monomer (b-3) is 0 to 90% byweight, preferably 0 to 10% by weight, and more preferably 0% by weightper the total amount of the monomer mixture (b) in order to avoid thesituation where the strength of the curable composition to be finallyobtained is difficult to be sufficiently improved due to the relativelydecreased use amount of the methacrylic alkyl ester monomer (b-1).

The cyano vinyl monomer (b-4) is a component to be used for finelyadjusting the compatibility between the graft copolymer (III) and thevinyl polymer (I).

As typical examples of the cyano vinyl monomer (b-4), there may bementioned, for example, acrylonitrile and methacrylonitrile, without anypurpose of restriction. These cyano vinyl monomers may be used alone ortwo or more of them are used as a mixture.

The use amount of the cyano vinyl monomer (b-4) is 0 to 25% by weightand preferably 0% by weight per the total amount of the monomer mixture(b) in order to avoid the situation where the strength of the curablecomposition to be finally obtained is difficult to be sufficientlyimproved due to the relatively decreased use amount of the methacrylicalkyl ester monomer (b-1).

As typical examples of the copolymerizable vinyl monomer (b-5), theremay be mentioned, for example, methyl acrylate, 4-hydroxybutyl acrylate,and glycidyl methacrylate, without any purpose of restriction. Thesevinyl monomers may be used alone or two or more of them are used as amixture.

The use amount of the copolymerizable vinyl monomer (b-5) is 0 to 25% byweight, preferably 0 to 10% by weight, and more preferably 0% by weightper the total amount of the monomer mixture (b) in order to avoid thesituation where the strength of the curable composition to be finallyobtained is difficult to be sufficiently improved due to the relativelydecreased use amount of the methacrylic alkyl ester.

As described, the graft copolymer (III) is obtained by graftcopolymerization of the rubber-like polymer [A] and the monomer mixture(b). The monomer mixture (b) gives the polymer [B] as a result of thegraft polymerization.

The use amounts of the rubber-like polymer [A] and the monomer mixture(b) are 50% by weight or more, preferably 60% by weight or more of therubber-like polymer [A] and, at the same time, 50% by weight or less,preferably 40% by weight or less of the monomer mixture (b),respectively, in order to sufficiently improve the strength of the curedproduct to be finally obtained from the vinyl polymer (I) of theinvention.

A method of obtaining the graft copolymer (III) is not particularlylimited and there may be mentioned, for example, a method involvingadding the monomer mixture (b) containing respectively desired amountsof the methacrylic alkyl ester monomer (b-1), the acrylic alkyl estermonomer (b-2), the aromatic vinyl monomer (b-3), the cyano vinyl monomer(b-4), and the copolymerizable vinyl monomer (b-5) to the above-producedrubber latex [A′] containing the rubber-like polymer [A] having a glasstransition temperature of 0° C. or lower, and then adding the samepolymerization initiator as above-mentioned one, or the like forcarrying out polymerization in a normal manner in order to obtain agraft copolymer in a powder form from the graft copolymer latex, and thelike methods.

The addition and polymerization of the monomer mixture (b) may becarried out in one stage or in multi-stages, without any purpose ofparticular restriction. The addition of the monomer mixture (b) may bebatch-wise or continuous, or in two- or more-steps each of these stepsbeing carried out in a combination of the above-mentioned two methods,without any purpose of particular restriction.

The reaction temperature is preferably 20 to 90° C., more preferably 30to 70° C., and further preferably 40 to 60° C.

The average particle diameter of the graft copolymer (III) obtained insuch a manner is preferable in a range from 0.03 to 0.28 μm.

A method for obtaining the graft copolymer (III) of the invention in apowder form is not particularly limited and the graft copolymer (III) ina powder form can be obtained, for example, by coagulation with an acidor a salt followed by a heat treatment, a dehydration treatment and/or adrying treatment etc., or a spray drying treatment; by coagulationfollowed by a dehydration treatment, and then followed by a melting; orby the like method.

The use amount of the graft copolymer (III) is in a range of preferably1 to 200 parts by weight, and more preferably 1 to 50 parts by weight,per 100 parts by weight of the vinyl polymer (I). If the use amount ofthe graft copolymer (III) exceeds 200 parts by weight, the viscosity ofthe curable composition becomes high and the workability tends to belowered.

<<Polyoxyalkylene Polymer (IV) Containing at Least One CrosslinkableSilyl Group>>

The polyoxyalkylene polymer (IV) containing a crosslinkable silylgroup(s) (also referred to as a polyoxyalkylene polymer (IV)), which isused in the present invention, is described in such patent documents asJapanese Kokoku Publication Sho-45-36319, Japanese Kokoku PublicationSho-46-12154, Japanese Kokoku Publication Sho-49-32673, Japanese KokaiPublication Sho-50-156599, Japanese Kokai Publication Sho-51-73561,Japanese Kokai Publication Sho-54-6096, Japanese Kokai PublicationSho-55-82123, Japanese Kokai Publication Sho-55-123620, Japanese KokaiPublication Sho-55-125121, Japanese Kokai Publication Sho-55-131022,Japanese Kokai Publication Sho-55-135135 and Japanese Kokai PublicationSho-55-137129.

Preferably, the molecular chain of the polyoxyalkylene polymer (IV) isessentially constituted of a repeating unit represented by the generalformula:

—R²⁶—O—

(wherein R²⁶ is a bivalent organic group). R²⁶ is preferably a bivalenthydrocarbon group containing 3 to 6 carbon atoms, more preferably mostlya hydrocarbon group containing 3 or 4 carbon atoms. Specific examples ofR²⁶ are —CH(CH₃)—CH₂—, —CH(C₂H₅)—CH₂—, —C(CH₃)₂—CH₂— and—CH₂—CH₂—CH₂—CH₂—. The molecular chain of the polyoxyalkylene polymer(IV) may be constituted of one single repeating unit species or two ormore repeating unit species. The group —CH(CH₃)—CH₂— is preferred as R²⁶particularly because the polymer viscosity can be adequately reduced andthe cured product can be provided with an appropriate level offlexibility by using that group.

The polyoxyalkylene polymer (IV) may be straight or branched or of astraight/branched mixed type. Some other monomer unit(s), for instance,may be contained therein. For attaining good workability and/orrendering the cured product flexible, however, the content of therepeating unit represented by —CH(CH₃)—CH₂—O— in the polymer ispreferably not lower than 50% by weight, more preferably not lower than80% weight.

The crosslinkable silyl group occurring in the polyoxyalkylene polymer(IV) and capable of being crosslinked under formation of a siloxane bondmay be the same as the crosslinkable silyl group in the vinyl polymer(I). Thus, mention may be made of a group represented by the generalformula 1:

—[Si(R¹)_(2-b)(Y)_(b)O]_(l)—Si(R²)_(3-a)(Y)_(a)  (1)

(wherein R¹ and R² are the same or different and each represents analkyl group containing 1 to 20 carbon atoms, an aryl group containing 6to 20 carbon atoms, an aralkyl group containing 7 to 20 carbon atoms ora triorganosiloxy group represented by (R′)₃SiO— (in which R′ is ahydrocarbon group containing 1 to 20 carbon atoms and the three R′groups may be the same or different) and when there are two or more R¹or R² groups, they may be the same or different; Y represents a hydroxylgroup or a hydrolyzable group and when there are two or more Y groups,they may be the same or different; a represents 0, 1, 2 or 3, represents0, 1 or 2; l is an integer of 0 to 19; provided that the relation a+lb≧1should be satisfied).

The hydrolyzable group includes, among others, a hydrogen atom andgroups in conventional use, such as alkoxy, acyloxy, ketoximate, amino,amide, aminoxy, mercapto and alkenyloxy groups. Among these, alkoxy,amide and aminoxy groups are preferred, and alkoxy groups areparticularly preferred in view of their mild hydrolyzability and easyhandleability.

One to three of such hydrolyzable groups and hydroxyl groups can bebound to each silicon atom, and the sum (a+Σb) is preferably within therange of 1 to 5. In cases where there are two or morehydrolyzable/hydroxyl groups bound in the crosslinkable silyl group,they may be the same or different. The number of crosslinkable silylgroup-constituting silicon atoms is at least 1 and, when a plurality ofsilicon atoms are linked together by siloxane bonding or the like, thenumber of silicon atoms is preferably not greater than 20. Inparticular, crosslinkable silyl groups represented by the generalformula 7:

—Si(R²)_(3-a)(Y)_(a)  (7)

(wherein R² and Y are as defined above; and a represents 1, 2 or 3): arepreferred because of their ready availability.

Considering the curability, the integer a is preferably 2 or more,although this is not critical. One in which a is 3 (e.g. trimethoxyfunctional group) is faster in curability than one in which a is 2 (e.g.dimethoxy functional group) but, as for the storage stability and/ormechanical properties (e.g. elongation), one in which a is 2 issometimes superior. For attaining a balance between curability andphysical properties, one in which a is 2 (e.g. dimethoxy functionalgroup) and one in which a is 3 (e.g. trimethoxy functional group) may beused in combination.

The average number of the crosslinkable silyl groups occurring in thepolyoxyalkylene polymer (IV) is preferably at least one, more preferablywithin the range of 1.1 to 5, per molecule of that polymer. When thenumber of the crosslinkable silyl groups contained in thepolyoxyalkylene polymer (IV) is smaller than 1, the curability becomesinsufficient and the desired good rubber elasticity behavior can hardlybe displayed. On the other hand, when it is larger than 5, the curedproduct becomes hard and the applicability to joints unfavorablydecreases.

The crosslinkable silyl groups may occur terminally or internally in themolecular chain of the polyoxyalkylene polymer (IV). When thecrosslinkable silyl groups occur at molecular chain termini, theeffective network chain content resulting from the polyoxyalkylenepolymer (IV) in the finally formed cured product becomes high and, thus,it becomes easy to obtain rubbery cured products high in strength, highin elongation and low in elastic modulus.

The number average molecular weight (Mn) of the polyoxyalkylene polymer(IV) is not particularly restricted but, generally, it may be within therange of 500 to 100,000. From the low polymer viscosity and/or curedproduct rubber elasticity viewpoint, however, it is preferably withinthe range of 2,000 to 60,000, more preferably within the range of 5,000to 30,000. The number average molecular weight of the polyoxyalkylenepolymer (IV), so referred to herein, is the value determined by gelpermeation chromatography (GPC) on the polystyrene equivalent basis. Themolecular weight distribution (Mw/Mn) is desirably narrow, preferablynot wider than 1.6, from the workability and/or cured product elongationviewpoint.

The crosslinkable silyl group-containing polyoxyalkylene polymer (IV) ispreferably prepared by introducing a crosslinkable silyl group into afunctional group-containing polyoxyalkylene polymer.

The functional group-containing polyoxyalkylene polymer can be obtainedby the conventional method of polymerization (anionic polymerizationusing a caustic alkali) for producing polyoxyalkylene polymers or by thechain extension reaction method using this polymer as the raw materialor, further, by polymerization techniques using a porphyrin-aluminumcomplex catalyst as typically described in Japanese Kokai PublicationSho-61-197631, Japanese Kokai Publication Sho-61-215622, Japanese KokaiPublication Sho-61-215623, Japanese Kokai Publication Sho-61-218632 andthe like, a double metal cyanide complex catalyst as typically disclosedin Japanese Kokoku Publication Sho-46-27250 and Japanese KokokuPublication Sho-59-15336, or a polyphosphazene salt catalyst astypically disclosed in Japanese Kokai Publication Hei-10-273512, amongothers. For practical purposes, the technique employing a double metalcyanide complex catalyst is preferred. The molecular weight distributionof the crosslinkable silyl group-containing oxyalkylene polymer (IV) isdependent on the molecular weight distribution of the precursor polymerprior to introduction of the crosslinkable silyl group and, therefore,the molecular weight distribution of the precursor polymer is preferablyas narrow as possible.

The introduction of crosslinkable silyl groups can be achieved by aknown technique. Thus, for example, the following techniques can bementioned.

(F) An oxyalkylene polymer having functional group such as hydroxylgroup at molecular terminus is reacted with an organic compound havingboth an active group reactive with the above functional group and anunsaturated group. To the obtained reaction product is then added acrosslinkable silyl group-containing hydrosilane compound in thepresence of a hydrosilylation catalyst in order to introduce acrosslinkable silyl group into the polymer terminus.

(G) An oxyalkylene polymer having a hydroxyl, epoxy, isocyanato, or thelike functional group (hereinafter referred to as Z functional group) ata molecular terminus is reacted with a silicon compound having both afunctional group (hereinafter referred to as Z′ functional group) whichis reactive with said Z functional group and a crosslinkable silyl groupin order to introduce a crosslinkable silyl group into the polymerterminus.

As the silicon compound having both the above Z′ functional group and acrosslinkable silyl group, there can be mentioned, but not particularlylimited to, amino group-containing silanes such asN-(β-aminoethyl)-γ-aminopropyltrimethoxysilane,N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane andγ-aminopropyltriethoxysilane; mercapto group-containing silanes such asγ-mercaptopropyltrimethoxysilane andγ-mercaptopropylmethyldimethoxysilane; epoxysilanes such asγ-glycidoxypropyltrimethoxysilane and2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; vinyl typeunsaturation-containing silanes such as vinyltriethoxysilane,γ-methacryloyloxypropyltrimethoxysilane, andγ-acryloyloxypropylmethyldimethoxysilane; chlorine atom-containingsilanes such as γ-chloropropyltrimethoxysilane; isocyanatogroup-containing silanes such as γ-isocyanatopropyltriethoxysilane, andγ-isocyanatopropylmethyldimethoxysilane; and hydrosilanes such asmethyldimethoxysilane, trimethoxysilane, and methyldiethoxysilane; amongothers.

Among the methods described above, the method (F) or the method (G)according to which a hydroxyl group-terminated polyoxyalkylene polymeris reacted with an isocyanato group- and crosslinkable silylgroup-containing compound is preferred from the economy and/or efficientreaction progress viewpoint.

The polyoxyalkylene polymer (IV) may contain an acryl-modifiedpolyoxyalkylene polymer in order to provide weather resistance andpressure sensitive adhesiveness. The acryl-modified polyoxyalkylenepolymer is a polyoxyalkylene polymer obtained by blending copolymerscomposed of radical-polymerized alkyl(meth)acrylate monomers.

The polyoxyalkylene polymer (IV) is used in an amount preferably withinthe range of 0 to 1,000 parts by weight, more preferably within therange of 0 to 400 parts by weight, per 100 parts by weight of the vinylpolymer (I). When the polyoxyalkylene polymer (IV) amounts to 0 part byweight, namely when it is not used, the weather resistance is very good.When the polyoxyalkylene polymer (IV) is used in combination, theworkability is improved and the elongation at break and the tearingstrength of the cured product is increased and, therefore, thecomposition becomes suited for use as a sealing material and gasket.

<<Tin Curing Catalyst (V)>>

A tin curing catalyst (V) may further be incorporated in the curablecomposition of the present invention.

As examples of the tin curing catalyst (V), there may be mentioned,among others, dialkyltin carboxylates such as dibutyltin dilaurate,dibutyltin diacetate, dibutyltin diethylhexanolate, dibutyltindioctoate, dibutyltin di(methyl maleate), dibutyltin di(ethyl maleate),dibutyltin di(butyl maleate), dibutyltin di(isooctyl maleate),dibutyltin di(tridecyl maleate), dibutyltin di(benzyl maleate),dibutyltin maleate, dioctyltin diacetate, dioctyltin distearate,dioctyltin dilaurate, dioctyltin di(ethyl maleate) and dioctyltindi(isooctyl maleate); dialkyltin oxides, for example dibutyltin oxide,dioctyltin oxide, and mixtures of dibutyltin oxide and a phthalateester; reaction products derived from a tetravalent tin compound, forexample an dialkyltin oxides or dialkyltin diacetate, and a hydrolyzablesilyl group-containing low-molecular-weight silicon compound, forexample tetraethoxysilane, methyltriethoxysilane,diphenyldimethoxysilane or phenyltrimethoxysilane; bivalent tin compoundsuch as stannous octylate, stannous naphthenate and stannous stearate;monoalkyltins, for example monobutyltin compounds such as monobutyltintrisoctoate and monobutyltin triisopropoxide, and monooctyltincompounds; reaction products and mixtures derived from an amine compoundand an organotin compound, for example the reaction product derived fromor mixtures of laurylamine and stannous octylate; chelate compounds suchas dibutyltin bisacetylacetonate, dioctyltin bisacetylacetonate,dibutyltin bisethylacetonate and dioctyltin bisethylacetonate; tinalcoholates such as dibutyltin dimethylate, dibutyltin diethylate,dioctyltin dimethylate and dioctyltin diethylate; and the like.

Among those mentioned above, dibutyltin bisacetylacetonate and likechelate compounds and tin alcoholates are highly active as silanolcondensation catalysts and, therefore, are preferred. Dibutyltindilaurate is preferred because of the low coloration of the curablecomposition obtained therefrom, low cost and ready availability.

These tin curing catalysts (V) may be used singly or two or more of themmay be used in combination.

The level of addition of such tin curing catalyst (V) is preferablyabout 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts byweight, per 100 parts by weight of the vinyl polymer (I). When theaddition level of the tin curing catalyst is less than 0.1 part byweight, the effect of the curing catalyst can hardly be exerted to asatisfactory extent in some cases. Conversely, when the level ofaddition of the tin curing catalyst exceeds 20 parts by weight, localheat generation and/or foaming may occur in the step of curing, makingit difficult to obtain good cured products; in addition, the pot lifebecomes excessively short, and the workability tends to deteriorate.

<<Curable Composition>>

In the curable composition of the invention, a curing catalyst and/or acuring agent appropriate for the respective crosslinkable functionalgroup species are/is sometimes required. There may further beincorporated one or more of compounding ingredients according to thephysical properties desired.

<Curing Catalyst, Curing Agent>

The crosslinkable silyl group-containing polymer is crosslinked andcured under siloxane bond formation in the presence or absence ofvarious condensation catalysts known in the art. The properties of thecured products can widely range from rubber-like to resinous onesaccording to the molecular weight and main chain skeleton of thepolymer.

As examples of such condensation catalyst except for the above-mentionedtin curing catalysts (V), there may be mentioned, among others, titanateesters such as tetrabutyl titanate and tetrapropyl titanate;organoaluminum compounds such as aluminum trisacetylacetonate, aluminumtris(ethyl acetoacetate) and diisopropoxyalminium ethyl acetoacetate;chelate compounds such as zirconium tetraacetylacetonate and titaniumtetraacetylacetoante; lead octylate; amine compounds such as butylamine,octylamine, laurylamine, dibutylamine, monoethanolamine, diethanolamine,triethanolamine, diethylenetriamine, triethylenetetramine, oleylamine,cyclohexylamine, benzylamine, diethylaminopropylamine, xylylenediamine,triethylenediamine, guanidine, diphenylguanidine,2,4,6-tris(dimethylaminomethyl)phenol, morpholine, N-methylmorpholine,2-ethyl-4-methylimidazole and 1,8-diazabicyclo[5.4.0]undecene-7 (DBU),or salts of these amine compounds with carboxylic acids;low-molecular-weight polyamide resins obtained from a polyamine inexcess and a polybasic acid; reaction products from a polyamine inexcess and an epoxy compound; amino group-containing silane couplingagents such as γ-aminopropyltrimethoxysilane andN-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; and like silanolcondensation catalysts and, further, other known silanol condensationcatalysts such as acidic catalysts and basic catalysts.

These catalysts may be used singly or two or more of them may be used incombination. These catalysts may also be used in combination with thetin curing catalyst (V). The level of addition of such condensationcatalyst is preferably about 0.1 to 20 parts by weight, more preferably0.5 to 10 parts by weight, per 100 parts by weight of the vinyl polymer(I). When the addition level of the condensation catalyst is less than0.1 part by weight, the effect of the condensation catalyst can hardlybe exerted to a satisfactory extent in some cases.

Conversely, when the level of addition of the condensation catalystexceeds 20 parts by weight, local heat generation and/or foaming mayoccur in the step of curing, making it difficult to obtain good curedproducts; in addition, the pot life becomes excessively short, and theworkability tends to deteriorate.

For further increasing the activity of the condensation catalyst in thecurable composition of the present invention, a silanol group-freesilicon compound represented by the general formula 23:

(R²⁷ _(c)Si(OR²⁸)_(4-c)  (23)

(wherein R²⁷ and R²⁸ each independently is a substituted orunsubstituted hydrocarbon group containing 1 to 20 carbon atoms; whentwo or more groups R²⁷ or R²⁸ are present, they may be the same ordifferent; and c is 0, 1, 2 or 3) may be added to the composition.

The above silicon compound is not restricted but those compounds of thegeneral formula 23 in which R²⁷ is an aryl group containing 6 to 20carbon atoms, such as phenyltrimethoxysilane,phenylmethyldimethoxysilane, phenyldimethylmethoxysilane,diphenyldimethoxysilane, diphenyldiethoxysilane andtriphenylmethoxysilane, are preferred since their accelerating effect onthe curing reaction of the composition is significant. In particular,diphenyldimethoxysilane and diphenyldiethoxysilane are low in cost andreadily available, hence are most preferred.

The level of addition of this silicon compound is preferably about 0.01to 20 parts by weight, more preferably 0.1 to 10 parts by weight, per100 parts by weight of the vinyl polymer (I). When the level of additionof the silicon compound is below this range, the curingreaction-accelerating effect may decrease in certain cases. When,conversely, the level of addition of the silicon compound exceeds thisrange, the hardness and/or tensile strength of the cured products mayfall.

<Adhesion Promoter>

A silane coupling agent and/or an adhesion promoter other than silanecoupling agents may be incorporated in the curable composition of theinvention. By adding an adhesion promoter, it becomes possible tofurther reduce the possibility that the sealant will peel off from theadherend, such as a siding board, as a result of changes in joint widthdue to external forces. In some cases, it becomes unnecessary to use aprimer for improving the adhesion; simplification of construction worksis thus expected.

As specific examples of the silane coupling agent, there may bementioned isocyanato group-containing silanes such asγ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane,γ-isocyanatopropylmethyldiethoxysilane andγ-isocyanatopropylmethyldimethoxysilane; amino group-containing silanessuch as γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane,γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane,N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane,N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane,N-(β-aminoethyl)-γ-aminopropyltriethoxysilane,N-(β-aminoethyl)-γ-aminopropylmethyldiethoxysilane,γ-ureidopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane,N-benzyl-γ-aminopropyltrimethoxysilane andN-vinylbenzyl-γ-aminopropyltriethoxysilane; mercapto group-containingsilanes such as γ-mercaptopropyltrimethoxysilane,γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilaneand γ-mercaptopropylmethyldiethoxysilane; epoxy group-containing silanessuch as γ-glycidoxypropyltrimethoxysilane,γ-glycidoxypropyltriethoxysilane,γ-glycidoxypropylmethyldimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and2-(3,4-epoxycyclohexyl)ethyltriethoxysilane; carboxysilanes such asβ-carboxyethyltriethoxysilane,β-carboxyethylphenylbis(2-methoxyethoxy)silane,N-β-(carboxymethyl)aminoethyl-γ-aminopropyltrimethoxysilane, vinylicunsaturated group-containing silanes such as vinyltrimethoxysilane,vinyltriethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane andγ-acryloyloxypropylmethyltriethoxysilane; halogen-containing silanessuch as γ-chloropropyltrimethoxysilane; isocyanuratosilanes such astris(trimethoxysilyl)isocyanurate, and the like. Modificationderivatives of these, for example amino-modified silyl polymers,silylated aminopolymers, unsaturated aminosilane complexes,phenylamino-long chain alkylsilanes, aminosilylated silicones, silylatedpolyesters and the like, can also be used as silane coupling agents.

The silane coupling agent is used, per 100 parts by weight of the vinylpolymer (I), preferably in an amount within the range of 0.1 to 20 partsby weight, more preferably 0.5 to 10 parts by weight.

As for the effect of the silane coupling agent added to the curablecomposition of the invention, it produces marked adhesive propertyimproving effects under non-primer or primer-treated conditions when thecomposition is applied to various adherend materials, namely inorganicmaterials such as glass, aluminum, stainless steel, zinc, copper andmortar, or organic materials such as polyvinyl chloride, acrylics,polyesters, polyethylene, polypropylene and polycarbonates. When it isused under non-primer conditions, the improving effects on theadhesiveness to various adherends are particularly remarkable.

Specific examples other than the silane coupling agent include, but arenot particularly limited to, epoxy resins, phenol resins, sulfur, alkyltitanates and aromatic polyisocyanates, among others.

The adhesion promoters specifically mentioned above may be used singlyor two or more of them may be used in admixture.

By adding these adhesion promoters, it is possible to improve theadhesiveness to adherends. Among the adhesion promoters mentioned above,silane coupling agents are preferably used in combination in an amountof 0.1 to 20 parts by weight to improve the adhesion, in particular theadhesion to the metal adherend surface such as the oil pan surface,although this is not critical.

<<Plasticizer>>

One or more of various plasticizers may be incorporated in the curablecomposition of the invention. The use of a plasticizer in combinationwith a filler, which is described later herein, can make it possible toincrease the elongation of cured products and/or incorporate a largeamount of a filler in the curable composition, hence is advantageous butnot critical.

The plasticizers are not particularly restricted but may be selectedfrom among the following ones according to the purpose of adjustingphysical and other properties: phthalate esters such as dibutylphthalate, diheptyl phthalate, di(2-ethylhexyl)phthalate, diisodecylphthalate and butyl benzyl phthalate; nonaromatic dibasic acid esterssuch as dioctyl adipate, dioctyl sebacate, dibutyl sebacate and isodecylsuccinate; aliphatic esters such as butyl oleate and methylacetylricinoleate; polyalkylene glycol esters such as diethylene glycoldibenzoate, triethylene glycol dibenzoate and pentaerythritol esters;phosphate esters such as tricresyl phosphate and tributyl phosphate;trimellitate esters; polystyrenes such as polystyrene andpoly-α-methylstyrene; polybutadiene, polybutene, polyisobutylene,butadiene-acrylonitrile copolymers, polychloroprene; chlorinatedparaffins; alkyldiphenyls, partially hydrogenated terphenyl and likehydrocarbon oils; process oils; polyethers including polyether polyolssuch as polyethylene glycol, polypropylene glycol and polytetramethyleneglycol and derivatives of such polyether polyols as resulting fromconversion of the hydroxyl group(s) thereof to an ester group, an ethergroup or like group; epoxy plasticizers such as epoxidized soybean oiland benzyl epoxystearate; polyester type plasticizers obtained from adibasic acid such as sebacic acid, adipic acid, azelaic acid or phthalicacid and a dihydric alcohol such as ethylene glycol, diethylene glycol,triethylene glycol, propylene glycol or dipropylene glycol; acrylicplasticizers; other vinyl polymers obtained by polymerizing a vinylmonomer(s) by various methods of polymerization; and the like.

By adding a high-molecular-weight plasticizer, which is a polymer havinga number average molecular weight of 500 to 15,000, it becomes possibleto adjust the viscosity and/or slump tendency of the curable compositionas well as the mechanical properties, such as tensile strength andelongation, of the cured products obtained by curing that compositionand, further, as compared with the cases where a low-molecular-weightplasticizer containing no polymer component within the molecule is used,it becomes possible to maintain the initial physical properties for along period of time. In the case of outdoor and the like use,plasticizer bleeding out onto the surface is prevented and, accordingly,dust hardly adhere to the surface and, also in the case of applicationof a paint or the like to the surface of the curable composition, coatfilm softening or coat film staining resulting therefrom hardly occursand, therefore, the beautiful view can be maintained for a long periodof time. This high-molecular-weight plasticizer may have a functionalgroup(s) or may not have any functional group, without any limitation.

The number average molecular weight of the above-mentionedhigh-molecular-weight plasticizer, which may be within the range of 500to 15,000, as mentioned above, is preferably 800 to 10,000, morepreferably 1,000 to 8,000. When the molecular weight is too low, theplasticizer will flow out upon exposure to heat and/or rain with thelapse of time, failing to maintain the initial physical properties for along period of time. When the molecular weight is excessively high, theviscosity increases, and the workability deteriorates.

Among these high-molecular-weight plasticizers, ones compatible with thevinyl polymer (I) are preferable. Among these, vinyl polymers arepreferable from the viewpoint of compatibility, weather resistance andheat resistance. Among vinyl polymers, (meth)acrylic polymers arepreferred and acrylic polymers are further preferred. These acrylicpolymers include, among others, conventional ones obtainable by solutionpolymerization, solventless acrylic polymers and the like. The latteracrylic plasticizers are more suited for the purpose of the presentinvention since they are produced by high-temperature continuouspolymerization techniques (U.S. Pat. No. 4,414,370, Japanese KokaiPublication Sho-59-6207, Japanese Kokoku Publication Hei-05-58005,Japanese Kokai Publication Hei-01-313522, U.S. Pat. No. 5,010,166),without using any solvent or chain transfer agent. Examples thereof arenot particularly restricted but include, among others, ARUFON UP-1000,UP-1020, UP-1110 and the like (these three are products of Toagosei Co.,Ltd.), JDX-P1000, JDX-P1110, JDX-P1020 and the like (these three areproducts of Johnson Polymer Corporation), and the like. Mention may ofcourse be made of the living radical polymerization technique as anothermethod of synthesis. This technique is preferred, since it can givepolymers with a narrow molecular weight distribution and a reducedviscosity and, furthermore, the atom transfer radical polymerizationtechnique is more preferred, although the polymerization technique isnot limited to those mentioned above.

The molecular weight distribution of the high-molecular-weightplasticizer is not particularly restricted but it is preferably narrow,namely lower than 1.8, more preferably not higher than 1.7, still morepreferably not higher than 1.6, still further preferably not higher than1.5, particularly preferably not higher than 1.4, most preferably nothigher than 1.3.

The plasticizers, including the high-molecular-weight plasticizersmentioned above, may be used singly or two or more of them may be usedin combination, although the use thereof is not always necessary. Ifnecessary, it is also possible to use a high-molecular-weightplasticizer and, further, a low-molecular-weight plasticizer incombination unless the physical properties are adversely affected.

The incorporation of such a plasticizer(s) may also be done on theoccasion of polymer production.

When a plasticizer is used, the amount thereof is not restricted butgenerally 5 to 800 parts by weight, preferably 10 to 600 parts byweight, more preferably 10 to 500 parts by weight, per 100 parts byweight of the vinyl polymer (I). When it is smaller than 5 parts byweight, the plasticizing effect tends to be hardly produced and, when itexceeds 800 parts by weight, the mechanical strength of cured productstends to become insufficient.

<Filler>

In the curable composition of the invention, there may be incorporatedone or more of various fillers, according to need, as long as thecurable composition obtained therefrom is transparent.

Specifically, there may be mentioned high-purity fused quartz glassfiller microparticles, high-purity crystalline quartz fillers and thelike, and FUSELEX and CRYSTALITE of TATSUMORI Co., Ltd., and the likemay be mentioned as commercial products.

When a filler is used, the filler is preferably used in an amount withinthe range of 0 to 400 parts by weight, more preferably within the rangeof 0 to 250 parts by weight, particularly preferably within the range of0 to 100 parts by weight, per 100 parts by weight of the vinyl polymer(I). When the addition level exceeds 400 parts by weight, theworkability of the curable composition may deteriorate.

Those fillers may be used singly or two or more of them may be used incombination.

<Physical Property Modifier>

In the curable composition of the invention, there may be incorporated aphysical property modifier capable of adjusting the tensile propertiesof the resulting cured products, according to need.

The physical property modifiers are not particularly restricted butinclude, for example, alkylalkoxysilanes such as methyltrimethoxysilane,dimethyldimethoxysilane, trimethylmethoxysilane andn-propyltrimethoxysilane; alkylisopropenoxysilanes such asdimethyldiisopropenoxysilane, methyltriisopropenoxysilane,γ-glycidoxypropylmethyldiisopropenoxysilane, functional group-containingalkoxysilanes such as γ-glycidoxypropylmethyldimethoxysilane,γ-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane,vinyldimethylmethoxysilane, γ-aminopropyltrimethoxysilane,N-(β-aminoethyl)aminopropylmethyldimethoxysilane,γ-mercaptopropyltrimethoxysilane andγ-mercaptopropylmethyldimethoxysilane; silicone varnishes;polysiloxanes; and the like. By using such as a physical propertymodifier, it is possible to increase the hardness of the cured productsafter curing of the curable composition of the invention or decreasesuch hardness and attain extensibility. Such physical property modifiersas mentioned above may be used singly or two or more of them may be usedin combination.

The content of the physical property modifier is not particularlyrestricted but the physical property modifiers can be used preferably inan amount within the range of 0.1 to 80 parts by weight, more preferably0.1 to 50 parts by weight, per 100 parts by weight of the vinyl polymer(I). When this amount is smaller than 0.1 part by weight, theweight-reducing effect is slight and, when it exceeds 80 parts byweight, decreases in tensile strength, among the mechanical propertiesafter curing of the formulations, are observed in some instances.

<Silanol-Containing Compound>

A silanol-containing compound may optionally be added into the curablecomposition of the present invention.

The silanol-containing compound means a compound having one silanolgroup in a molecule and/or a compound capable of forming a compoundhaving one silanol group in a molecule by a reaction with moisture. Whenthese compounds are used, only one of the above two compounds may beused, or both of them may be used simultaneously.

The compounds having one silanol group in a molecule is not particularlyrestricted. Among others, there may be mentioned compounds which can berepresented by the formula (R″)₃SiOH (wherein R″s are the same ordifferent kind of substituted or non-substituted alkyl or aryl group),for example, the following compounds:

(CH₃)₃SiOH, (CH₃CH₂)₃SiOH, (CH₃CH₂CH₂)₃SiOH, (n-Bu)₃SiOH, (sec-Bu)₃SiOH,(t-Bu)₃SiOH, (t-Bu)Si(CH₃)₂OH, (C₅H₁,)₃SiOH, (C₆H₁₃)₃SiOH, (C₆H₅)₃SiOH,(C₆H₅)₂Si(CH₃)OH, (C₆H₅)Si(CH₃)₂OH, (C₆H₅)₂Si(C₂H₅)OH, C₆H₅Si(C₂H₅)₂OH,C₆H₅CH₂Si(C₂H₅)₂OH, C₁₀H₇Si (CH₃)₂OH,(wherein C₆H₅ represents phenyl group and C₁₀H₇ represents a naphthylgroup;silanol group-containing cyclic polysiloxanes compounds, for example,the following compounds;

silanol group-containing chain polysiloxanes compounds, for example, thefollowing compounds:

(wherein R is the same as the definition for R²⁹; and m is a positivenumber):compounds the polymer main chain of which is composed of silicon andcarbon atoms and in which a silanol group is bonded at the molecularterminus, for example, the following compounds:

(wherein R is the same as the definition for R²⁹; and m is a positivenumber):compounds in which silanol group is bonded to the main chain ofpolysilane at a molecular terminus, for example, the followingcompounds:

(wherein m is a positive number):and compounds the polymer main chain of which is composed of silicon,carbon and oxygen atoms and in which a silanol group is bonded at themolecular terminus, for example, the following compounds:

(wherein each of m and n is a positive number): and the like. Amongthem, the compounds represented by the following general formula (24)are preferred.

(R²⁹)₃SiOH  (24)

(wherein R²⁹ represents a univalent hydrocarbon group containing 1 to 20carbon atoms, and a plurality of R²⁹ may be the same or different).

R²⁹ is preferably methyl, ethyl, vinyl, t-butyl or phenyl group, and, inview of ready availability and effects, more preferably methyl group.

It is presumed that flexibility of a cured product is given by areaction of a compound having one silanol group in one molecule with acrosslinkable silyl group of the vinyl polymer (I) or a siloxane bondformed by crosslinking, to thereby reduce crosslinking points.

The compounds capable of forming a compound having one silanol group ina molecule by a reaction with moisture are not particularly restricted,but are preferably compounds in which the compound having one silanolgroup in a molecule formed by a reaction with moisture (the compound isa hydrolysis product) is represented by the general formula (24). Forexample, the following compounds may be mentioned in addition to thecompounds represented by the general formula (25), as described below.However, these are not particularly limitative. Such compounds which maybe suitably used are N,O-bis(trimethylsilyl)acetamide,N-(trimethylsilyl)acetamide, bis(trimethylsilyl)trifluoroacetamide,N-methyl-N-trimethylsilyltrifluoroacetamide, bis(trimethylsilyl)urea,N-(t-butyldimethylsilyl)N-methyltrifluoroacetamide,(N,N-dimethylamino)trimethylsilane, (N,N-diethylamino)trimethylsilane,hexamethyldisilazane, 1,1,3,3-tetramethyldisilazane,N-(trimethylsilyl)imidazole, trimethylsilyltrifluoromethanesulfonate,trimethylsilylphenoxide, trimethylsilylated product of n-octanol,trimethylsilylated product of 2-ethylhexanol, tris(trimethylsilyl)atedproduct of glycerin, tris(trimethylsilyl)ated product oftrimethylolpropane, tris(trimethylsilyl)ated product of pentaerythritol,tetra(trimethylsilyl)ated product of pentaerythritol,(CH₃)₃SiNHSi(CH₃)₃, (CH₃)₃SiNSi(CH₃)₂, and the following compounds:

Among them, (CH₃)₃SiNHSi(CH₃)₃ is particularly preferred in view of anamount of contained silanol group in a hydrolysis product.

Furthermore, compounds capable of forming a compound having one silanolgroup in a molecule by a reaction with moisture are not particularlyrestricted, but the compounds represented by the following generalformula (25) are preferred in addition to the above compounds:

((R²⁹)₃SiO)_(q)R³⁰  (25)

(wherein R²⁹ is as defined above; q represents a positive number; andR³⁰ represents a group exclusive of a part of or all of the activehydrogen from an active hydrogen-containing compound). R²⁹ is preferablymethyl, ethyl, vinyl, t-butyl, or phenyl group, and more preferablymethyl group.

(R²⁹)₃SiO group is preferably trimethylsilyl group in which all threeR²⁹s are methyl group, and q is preferably 1 to 5.

Active hydrogen-containing compounds, which are origins of the aboveR³⁰, are not particularly restricted, but includes, among others,alcohols such as methanol, ethanol, n-butanol, i-butanol, t-butanol,n-octanol, 2-ethylhexanol, benzyl alcohol, ethylene glycol, diethyleneglycol, polyethylene glycol, propylene glycol, dipropylene glycol,polypropylene glycol, propanediol, tetramethylene glycol,polytetramethylene glycol, glycerin, trimethylolpropane andpentaerythritol; phenols such as phenol, cresol, bisphenol A andhydroquinone; carboxylic acids such as formic acid, acetic acid,propionic acid, lauric acid, palmitic acid, stearic acid, behenic acid,acrylic acid, methacrylic acid, oleic acid, linolic acid, linolenicacid, sorbic acid, oxalic acid, malonic acid, succinic acid, adipicacid, maleic acid, benzoic acid, phthalic acid, terephthalic acid andtrimellitic acid; ammonia; amines such as methylamine, dimethylamine,ethylamine, diethylamine, n-butylamine and imidazole; acid amides suchas acetamide and benzamide; ureas such as urea and N,N′-diphenylurea;and ketones such as acetone, acetylketone and 2,4-heptadione.

Although it is not particularly limited, a compound capable of forming acompound having one silanol group in a molecule by a reaction withmoisture, represented by the above general formula (25), is obtainableby, for example, subjecting the above-mentioned activehydrogen-containing compound or the like to the reaction with thecompound having a group capable of reacting with the active hydrogen,such as halogen group, together with a (R²⁹)₃Si group, which issometimes referred to as “silylating agent”, such as trimethylsilylchloride or dimethyl(t-butyl)silylchloride. In the above description,R²⁹ is the same one as defined above.

The compounds represented by the general formula (25) includesallyloxytrimethylsilane, N,O-bis(trimethylsilyl)acetamide,N-(trimethylsilyl)acetamide, bis(trimethylsilyl)trifluoroacetamide,N-methyl-N-trimethylsilyltrifluoroacetamide, bis(trimethylsilyl)urea,N-(t-butyldimethylsilyl)N-methyltrifluoroacetamide,(N,N-dimethylamino)trimethylsilane, (N,N-diethylamino)trimethylsilane,hexamethyldisilazane, 1,1,3,3,-tetramethyldisilazane,N-(trimethylsilyl)imidazole, trimethylsilyltrifluoromethanesulfonate,trimethylsilylphenoxide, trimethylsilylated product of n-octanol,trimethylsilylated product of 2-ethylhexanol, tris(trimethylsilyl)atedproduct of glycerin, tris(trimethylsilyl)ated product oftrimethylolpropane, tris(trimethylsilyl)ated product of pentaerythritol,tetra(trimethylsilyl)ated product of pentaerythritol, and the like.These may be used singly or in combination of two or more.

Additionally, the compounds which may be represented by the generalformula ((R³¹)₃SiO)(R³²O)_(s))_(t)D, CH₃O(CH₂CH(CH₃)O)₅Si(CH₃)₃,CH₂═CHCH₂(CH₂CH(CH₃)O)₅Si(CH₃)₃, (CH₃)₃SiO(CH₂CH(CH₃)O)₅Si(CH₃)₃, and(CH₃)₃SiO(CH₂CH(CH₃)O)₇Si (CH₃)₃

(wherein R³¹ represents the same or different kind of substituted orunsubstituted univalent hydrocarbon group; R³² is an bivalenthydrocarbon group containing 1 to 8 carbon atoms; s and t are positivenumbers, t is 1 to 6 and s times t is not less than 5; and D is an mono-to hexa-valent organic group) are also suitably used. These may be usedsingly or in combination of two or more.

Among the compounds capable of forming a compound having one silanolgroup in a molecule by a reaction with moisture, the active hydrogencompounds which is formed after hydrolysis are preferably phenols, acidamides and alcohols since there are no adverse affects on storagestability, weatherability or the like. More preferred are phenols andalcohols, in which the active hydrogen compound is a hydroxyl group.

Among the above compounds, preferred areN,O-bis(trimethylsilyl)acetamide, N-(trimethylsilyl)acetamide,trimethylsilylphenoxide, trimethylsilylated product of n-octanol,trimethylsilylated product of 2-ethylhexanol, tris(trimethylsilyl)atedproduct of trimethylolpropane, tris(trimethylsilyl)ated product ofpentaerythritol, tetra(trimethylsilyl)ated product of pentaerythritol,and the like.

The compounds capable of forming a compound having one silanol group ina molecule by a reaction with moisture produces the compound having onesilanol group in a molecule by reacting with moisture during storage, atthe time of curing, or after curing. It is presumed that flexibility ofa cured product is given by a reaction of the thus-formed compoundhaving one silanol group in a molecule with a crosslinkable silyl groupof the vinyl polymer (I) or a siloxane bond formed by crosslinking, tothereby reduce crosslinking points.

The addition level of the silanol-containing compound can be properlyadjusted depending on the expected physical properties of the curedproduct. The addition level of the silanol-containing compound is 0.1 to50 parts by weight, preferably 0.3 to 20 parts by weight and still morepreferably 0.5 to 10 parts by weight, per 100 parts by weight of thevinyl polymer (I). When the level is below 0.1 parts by weight, theeffects caused by addition may not appear, and on the contrary, when itexceeds 50 parts by weight, crosslinking may be insufficient andstrength or gel fraction ratio of the cured product tend to deteriorate.

The time to add the silanol compound into the vinyl polymer (I) is notparticularly restricted, but it may be added in the production processof the vinyl polymer (I), or may be added in the preparation process ofa curable composition.

<Thixotropic Agent (Antisagging Agent)>

If necessary, a thixotropic agent (antisagging agent) may be added tothe curable composition of the invention to prevent sagging and improvethe workability.

The thixotropic agents (antisagging agents) are not particularlyrestricted but include, for example, polyamide waxes, hydrogenatedcastor oil derivatives; metal soaps such as calcium stearate, aluminumstearate and barium stearate, and the like. These thixotropic agents(antisagging agent) may be used singly or two or more of them may beused in combination.

The addition level of the thixotropic agent is 0.1 to 50 parts byweight, and preferably 0.2 to 25 parts by weight, per 100 parts byweight of the vinyl polymer (I). When the level is below 0.1 parts byweight, the thixotropic effects may not appear sufficiently, and on thecontrary, when it exceeds 50 parts by weight, viscosity of theformulation may increase and storage stability of the formulation tendsto deteriorate.

<Photocurable Substance>

To the curable composition of the invention, there may be added aphotocurable substance, according to need. The photocurable substance isa substance whose molecular structure undergoes a chemical change in ashort time under the action of light and which thus causes changes ofphysical properties such as curing. By adding such photocurablesubstance, it becomes possible to reduce the tackiness (residual tack)of the cured product surface after curing of the curable composition.This photocurable substance is a substance capable of curing uponirradiation with light. A typical photocurable substance is a substancecapable of curing when allowed to stand at an indoor place in the sun(near a window) at room temperature for 1 day, for example. A largenumber of compounds of this type are known, including organic monomers,oligomers, resins, and compositions containing them, and they are notparticularly restricted in kind but include, for example, unsaturatedacrylic compounds, vinyl cinnamate polymers, azidated resins and thelike.

As the unsaturated acrylic compounds, there may be specificallymentioned, for example, (meth)acrylate esters of low-molecular-weightalcohols such as ethylene glycol, glycerol, trimethylolpropane,pentaerythritol and neopentyl alcohol; (meth)acrylate esters of alcoholsderived from acids such as bisphenol A, acids such as isocyanuric acidor such low-molecular-weight alcohols as mentioned above by modificationwith ethylene oxide and/or propylene oxide; (meth)acrylate esters ofhydroxyl-terminated polyether polyols whose main chain is a polyether,polymer polyols obtained by radical polymerization of a vinyl monomer(s)in a polyol whose main chain is a polyether, hydroxyl-terminatedpolyester polyols whose main chain is a polyester, polyols whose mainchain is a vinyl or (meth)acrylic polymer and which have hydroxyl groupsin the main chain, and like polyols; epoxy acrylate oligomers obtainedby reacting a bisphenol A-based, novolak type or other epoxy resin with(meth)acrylic acid; urethane acrylate type oligomers containing urethanebonds and (meth)acryl groups within the molecular chain as obtained byreacting a polyol, a polyisocyanate and a hydroxyl group-containing(meth)acrylate; and the like.

The vinyl cinnamate polymers are photosensitive resins whose cinnamoylgroups function as photosensitive groups and include cinnamicacid-esterified polyvinyl alcohol species and various other polyvinylcinnamate derivatives.

The azidated resins are known as photosensitive resins with the azidogroup serving as a photosensitive group and generally includephotosensitive rubber solutions with an azide compound added as aphotosensitive substance and, further, detailed examples are found in“Kankosei Jushi (Photosensitive Resins)” (published Mar. 17, 1972 byInsatsu Gakkai Shuppanbu, pages 93 ff, 106 ff, 117 ff). These can beused either singly or in admixture, with a sensitizer added, ifnecessary.

Among the photocurable substances mentioned above, unsaturated acryliccompounds are preferred in view of their easy handleability.

The photocurable substance is preferably added in an amount of 0.01 to30 parts by weight per 100 parts by weight of the vinyl polymer (I). Ataddition levels below 0.01 part by weight, the effects will beinsignificant and, at levels exceeding 30 parts by weight, the physicalproperties may be adversely affected. The addition of a sensitizer suchas a ketone or nitro compound or a promoter such as an amine can enhancethe effects in some instances.

<Air Oxidation-Curable Substance>

In the curable composition of the invention, there may be incorporatedan air oxidation-curable substance, if necessary.

The air oxidation-curable substance is a compound containing anunsaturated group capable of being crosslinked for curing by oxygen inthe air. By adding such air oxidation-curable substance, it becomespossible to reduce the tack (also referred as residual tack) of thecured product surface on the occasion of curing of the curablecomposition. This air oxidation-curable substance according to thepresent invention is a substance capable of curing upon contacting withair and, more specifically, has a property such that it cures as aresult of reaction with oxygen in the air. A typical airoxidation-curable substance can be cured upon allowing it to stand inthe air in a room for 1 day, for example.

As specific examples of the air oxidation-curable substance, there maybe mentioned, for example, drying oils such as tung oil and linseed oil;various alkyd resins obtained by modification of such drying oils;drying oil-modified acrylic polymers, epoxy resins, silicone resins;1,2-polybutadiene, 1,4-polybutadiene, C5-C8 diene polymers andcopolymers and, further, various modifications of such polymers andcopolymers (e.g. maleinated modifications, boiled oil modifications);and the like. Among these, tung oil, liquid ones among the dienepolymers (liquid diene polymers) and modifications thereof areparticularly preferred.

As specific examples of the liquid diene polymers, there may bementioned, for example, liquid polymers obtained by polymerization orcopolymerization of diene compounds such as butadiene, chloroprene,isoprene and 1,3-pentadiene, NBR, SBR and like polymers obtained bycopolymerization of such diene compounds (as main components) with amonomer copolymerizable therewith, such as acrylonitrile or styrene,and, further, various modification thereof (e.g. maleinatedmodifications, boiled oil modifications). These may be used singly ortwo or more of them may be used in combination. Among these liquid dienecompounds, liquid polybutadiene species are preferred.

The air oxidation-curable substances may be used singly or two or moreof them may be used in combination. The use of a catalyst capable ofpromoting the oxidation curing or a metal drier in combination with theair oxidation-curable substance can enhance the effects in certaininstances. As such catalysts or metal driers, there may be mentioned,for example, metal salts such as cobalt naphthenate, lead naphthenate,zirconium naphthenate, cobalt octylate and zirconium octylate, aminecompounds, and the like.

The air oxidation-curable substance is preferably added in an amount of0.01 to 30 parts by weight per 100 parts by weight of the vinyl polymer(I). At levels below 0.01 part by weight, the effects will beinsignificant and, at levels exceeding 30 parts by weight, the physicalproperties may be adversely affected.

<Antioxidant and Light Stabilizer>

In the curable composition of the invention, there may be incorporatedan antioxidant or a light stabilizer, if necessary.

Various of antioxidants and light stabilizers are known and mention maybe made of various species described, for example, in “SankaboshizaiHandbook (Handbook of Antioxidants)” published by Taiseisha LTD. and“Kobunshi Zairyo no Rekka to Anteika (Degradation and Stabilization ofPolymer Materials)” (pp. 235-242) published by CMC Publishing CO., LTD.The antioxidants and light stabilizers which can be used are not limitedto these, however.

As specific examples of these antioxidants, there may be mentioned, butnot restricted to, for example, thioether antioxidants such as AdekastabPEP-36 and Adekastab AO-23 (both being products of Asahi Denka Co.,Ltd.); phosphorus-containing antioxidants such as IRGAFOS 38, IRGAFOS168 and IRGAFOS P-EPQ (the three being products of Ciba SpecialtyChemicals); and hindered phenol antioxidants. For example, such hinderedphenol compounds as enumerated below are preferred.

As specific examples of the hindered phenol compounds, the following canbe mentioned.

2,6-Di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol,mono(or di or tri)(α-methylbenzyl)phenol,2,2′-methylenebis(4-ethyl-6-tert-butylphenol),2,2′-methylenebis(4-methyl-6-tert-butylphenol),4,4′-butylidenebis(3-methyl-6-tert-butylphenol),4,4′-thiobis(3-methyl-6-tert-butylphenol),2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, triethyleneglycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate],1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate],2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine,pentaerythrityltetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate],2,2-thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate],octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,N,N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxyhydrocinnamide),diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate,1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,bis(ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonato)calcium,tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,2,4-bis[(octylthio)methyl]-o-cresol,N,N′-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine,tris(2,4-di-tert-butylphenyl)phosphite,2-(5-methyl-2-hydroxyphenyl)benzotriazole,2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole,2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole,2-(3-tert-butyl-5-methyl-2-hydroxyphenyl)-5-chlorobenzotriazole,2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole,2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole,2-(2′-hydroxy-5′-tert-octylphenyl)benzotriazole, methyl3-[3-tert-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate-polyethyleneglycol (molecular weight about 300) condensate,hydroxyphenylbenzotriazole derivatives,bis(1,2,2,6,6-pentamethyl-4-piperidyl)2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-n-butylmalonate,2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, and thelike.

Examples of the relevant product names include, but are not limited to,Nocrac 200, Nocrac M-17, Nocrac SP, Nocrac SP-N, Nocrac NS-5, NocracNS-6, Nocrac NS-30, Nocrac 300, Nocrac NS-7 and Nocrac DAH (all beingproducts of Ouchi Shinko Chemical Industrial Co., Ltd.), AdekastabAO-30, Adekastab AO-40, Adekastab AO-50, Adekastab AO-60, AdekastabAO-616, Adekastab AO-635, Adekastab AO-658, Adekastab AO-80, AdekastabAO-15, Adekastab AO-18, Adekastab 328 and Adekastab AO-37 (all beingproducts of Asahi Denka Co., Ltd.), IRGANOX 245, IRGANOX 259, IRGANOX565, IRGANOX 1010, IRGANOX 1024, IRGANOX 1035, IRGANOX 1076, IRGANOX1081, IRGANOX 1098, IRGANOX 1222, IRGANOX 1330 and IRGANOX 1425WL (allbeing products of Ciba Specialty Chemicals), and Sumilizer GM andSumilizer GA-80 (both being products of Sumitomo Chemical Co., Ltd.).

As specific examples of the light stabilizers, there may be mentioned,for example, benzotriazole compounds such as TINUVIN P, TINUVIN 234,TINUVIN 320, TINUVIN 326, TINUVIN 327, TINUVIN 329 and TINUVIN 213 (allbeing products of Ciba Specialty Chemicals), triazines such as TINUVIN1577, benzophenone compounds such as CHIMASSORB 81, benzoate compoundssuch as TINUVIN 120 (all being products of Ciba Specialty Chemicals);hindered amine compounds, and the like ultraviolet absorbers.

Among them, hindered amine compounds are more preferred. As specificexamples of the hindered amine compounds, the following can bementioned, but there is no restriction, however; dimethylsuccinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidinepolycondensate,poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}],N,N′-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazinecondensate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate,bis(2,2,6,6-tetramethyl-4-piperidinyl)succinate and the like.

Examples of the relevant product names include, but are not limited to,TINUVIN 622LD, TINUVIN 144 and CHIMASSORB 944LD, CHIMASSORB 119FL (allbeing products of Ciba Specialty Chemicals), Adekastab LA-52, AdekastabLA-57, Adekastab LA-62, Adekastab LA-67, Adekastab LA-63, AdekastabLA-68, Adekastab LA-82 and Adekastab LA-87 (all being products of AsahiDenka Co., Ltd.), and Sanol LS-770, Sanol LS-765, Sanol LS-292, SanolLS-2626, Sanol LS-1114, Sanol LS-744 and Sanol LS-440 (all beingproducts of Sankyo Co., Ltd.), and the like.

The light stabilizer may be used in combination with the antioxidant,and such combined use enhances the effects thereof and may improve theheat resistance and the weather resistance, hence is particularlypreferred. Such ready-made mixtures of an antioxidant and a lightstabilizer as TINUVIN C353 and TINUVIN B75 (both being products of CibaSpecialty Chemicals) and the like may also be used.

An ultraviolet absorber and a hindered amine compound (HALS) aresometimes used in combination in order to improve the weatherresistance. The combined use of may produce enhanced effects and,therefore, both may be used in combination without any particularrestriction, and the combined use is sometimes favorable.

The antioxidants or light stabilizers to be used are not particularlyrestricted, but those having high molecular weight are preferred becausethey exhibit heat resistance-improving effect according to the presentinvention for long period of time.

The addition level of the antioxidants or the light stabilizer ispreferably within the range of 0.1 to 20 parts by weight per 100 partsby weight of the vinyl polymer (I), respectively. At levels below 0.1part by weight, the heat resistance-improving effect is insignificant,while levels exceeding 20 parts by weight make no great difference ineffect any longer, hence are economically disadvantageous.

<Other Additives>

If necessary, one or more of various additives may be added to thecurable composition of the invention for the purpose of adjustingvarious physical properties of the curable composition or curedproducts.

Such additives include, for example, flame retardants, curabilitymodifiers, antioxidants, radical scavengers, metal deactivators,antiozonants, phosphorus-containing peroxide decomposers, lubricants,pigments, blowing agents and the like. These various additives may beused singly or two or more of them may be used in combination.

Specific examples of such additives are described, for example inJapanese Kokoku Publication Hei-04-69659, Japanese Kokoku PublicationHei-07-108928, Japanese Kokai Publication Sho-63-254149 and JapaneseKokai Publication Sho-64-22904.

<Production of the Curable Composition>

As described above, the curable composition according to the presentinvention comprises a vinyl polymer (I) the main chain of which is theproduct of living radical polymerization and which contains at least onecrosslinkable silyl group, a micronized hydrophobic silica (II), or agraft copolymer (III) obtained by graft polymerization of acrosslinkable rubber-like acrylic ester polymer and a vinyl monomer.Alternatively, the curable composition may comprise all of theabove-mentioned vinyl polymer (I), micronized hydrophobic silica (II)and graft copolymer (III). Additionally, the curable composition mayfurther comprise a polyoxyalkylene polymer (IV) containing at least onecrosslinkable silyl group and/or a tin curing catalyst (V).

The curable composition of the invention may be prepared as a onepackage formulation, which is to be cured by the moisture in the airafter application, by compounding all the components/ingredients andtightly sealing in a container for storage, or as a two-pack typeformulation by separately preparing a curing agent by compounding acuring catalyst, a filler, a plasticizer, water and the like, so thatsuch composition and the polymer composition may be mixed together priorto use. In the case of such two-pack type, a colorant or colorants canbe added on the occasion of mixing of the two compositions. Thus, inproviding sealants matching in color to the given siding boards, forexample, a wide assortment of colors become available with limitedstocks and thus it becomes easy to cope with the market demand for manycolors; this is more favorable for low buildings and the like. By mixingthe colorant or colorants, for example a pigment or pigments, with aplasticizer and/or a filler, as the case may be, and using thethus-prepared paste, it becomes possible to facilitate the workingprocess. Furthermore, it is possible to finely adjust the curing rate byadding a retarder on the occasion of mixing up the two compositions.

The curable composition of the invention thus obtained is transparent.It may be particularly preferably used as a curable composition for atransparent material.

<<Cured Product>> <Use>

The curable composition of the present invention can be used in variousfields of application which include, but are not limited to, elasticsealing materials for building and construction and sealing materialsfor pair glass, adhesives, elastic adhesives, coating compositions,gaskets, casting materials, various molding materials, artificialmarble, rustproof and waterproof sealants for end faces (cut sections)of net glass or laminated glass, materials for vibrationabsorption/vibration suppression/noise reduction/seismic isolation usedin an automobile, a vessel, a household electrical appliance and thelike, a liquid sealing agent used in an automobile parts, an electricparts, various kinds of machine parts and the like, and the likeapplications. Among these, the curable composition can be more suitablyused as adhesives, sealing materials, liquid gaskets and coatingcompositions.

BEST MODE FOR CARRYING OUT THE INVENTION

The following examples illustrate the present invention in furtherdetail. These examples are, however, by no means limitative of the scopeof the invention.

In the examples and comparative examples below, “parts” and “%”represent “parts by weight” and “% by weight”, respectively.

In the examples below, the number average molecular weight and themolecular weight distribution (ratio of the weight average molecularweight to the number average molecular weight) were calculated by astandard polystyrene calibration method using gel permeationchromatography (GPC). In GPC measurement, a polystyrene-crosslinked gelcolumn (Shodex GPC K-804; manufactured by Showa Denko K. K.) andchloroform were used as a GPC column and a mobile solvent, respectively.

Synthesis Example 1

A 2-liter flask was charged with 8.39 g (58.5 mmol) of cuprous bromideand 112 mL of acetonitrile, and the contents were heated at 70° C. withstirring under a nitrogen stream for 30 minutes. Thereto were added 17.6g (48.8 mmol) of diethyl 2,5-dibromoadipate and 224 mL (1.56 mol) ofn-butyl acrylate, and the mixture was further heated at 70° C. withstirring for 45 minutes. Thereto was added 0.41 mL (1.95 mmol) ofpentamethyldiethylenetriamine (hereinafter referred to as “triamine”),and the reaction was thereby started. While continued heating at 70° C.with stirring, 895 mL (6.24 mol) of butyl acrylate was added dropwiseintermittently over 160 minutes beginning at 80 minutes after start ofthe reaction. During this dropping, 1.84 mL (8.81 mmol) of triamine wasadded. After the lapse of 375 minutes after start of the reaction, 288mL (1.95 mol) of 1,7-octadiene and 4.1 mL (19.5 mmol) of triamine wereadded, and the heating at 70° C. with stirring was further continued. At615 minutes after start of the reaction, the heating was stopped. Thereaction mixture was diluted with toluene and filtered, and the filtratewas heated under reduced pressure to give a polymer (polymer [1]). Thepolymer [1] had a number average molecular weight of 24,000 with amolecular weight distribution of 1.3. The number of alkenyl groups asdetermined by ¹H-NMR spectrometry was 2.6 per polymer molecule.

In a nitrogen atmosphere, a 2-liter flask was charged with the polymer[1], 11.9 g (0.121 mol) of potassium acetate and 900 mL ofN,N-dimethylacetamide (hereinafter referred to as “DMAc”), and themixture was heated at 100° C. with stirring for 11 hours. The DMAc wasremoved by heating the reaction mixture under reduced pressure, toluenewas added for filtration. An adsorbent (200 g, Kyowaad 700PEL, productof Kyowa Chemical) was added to the filtrate, and the mixture was heatedat 100° C. with stirring under a nitrogen stream for 3 hours. Theadsorbent was filtered off, and the toluene was distilled off from thefiltrate under reduced pressure to give a polymer (polymer [2]).

A one-liter pressure-resistant reaction vessel was charged with thepolymer [2] (648 g), dimethoxymethylhydrosilane (25.5 mL, 0.207 mol),methyl orthoformate (7.54 mL, 0.0689 mol) andplatinum(0)-1,1,3,3-tetramethyl-1,3-divinyldisiloxane complex. Theamount of the platinum catalyst used was such that the mole ratiothereof to the alkenyl group in the polymer amounted to 3×10⁻³equivalents. The mixture was heated at 100° C. with stirring for 2hours. The volatile matter was then distilled off from the mixture underreduced pressure, whereby a silyl group-terminated polymer (polymer A)was obtained.

The polymer obtained had a number average molecular weight of 30,000 asdetermined by GPC (on the polystyrene equivalent basis) with a molecularweight distribution of 1.8. The average number of the silyl groupsintroduced per polymer molecule as determined by ¹H-NMR spectrometry was1.9.

Synthesis Example 2

An alkenyl group-terminated vinyl copolymer [3] was obtained in the samemanner as in Synthesis Example 1 except that 3.40 g (23.7 mmol) ofcuprous bromide, 47 mL of acetonitrile, 7.80 g (21.7 mmol) of diethyl2,5-dibromoadipate, 368 mL (2.56 mol) of butyl acrylate, 38 mL (0.41mol) of methyl acrylate, 77 mL (0.19 mol) of stearyl acrylate, 2.475 mL(11.86 mmol) of triamine, 141 mL of acetonitrile, 58 mL (0.40 mol) of1,7-octadiene were used.

A silyl group-terminated n-butyl acrylate/methyl acrylate/stearylacrylate copolymer (polymer B) was obtained using the copolymer [3] (260g) obtained above, as well as dimethoxymethylhydrosilane (8.46 mL, 68.6mmol), methyl orthoformate (2.50 mL, 22.9 mmol) and a platinum catalyst.The copolymer obtained had a number average molecular weight of 23,000with a molecular weight distribution of 1.3. The average number of thesilyl groups introduced per polymer molecule as determined by ¹H-NMRspectrometry was about 1.7.

Synthesis Example 3

800 g of an allyl ether group-terminated polyoxypropylene of numberaverage molecular weight of about 19,000 was introduced into apressure-resistant reaction vessel equipped with a stirrer.Methyldimethoxysilane and 1×10⁻⁴ [eq/vinyl group] of a chloroplatinatecatalyst (chloroplatinate hexahydrate) were then added thereto and theresultant mixture was subjected to reaction for 2 hours at 90° C. toproduce a crosslinkable silyl group-containing polyoxyalkylene polymer(polymer C) having 2.1 methyldimethoxysilyl groups, on average, in onemolecule.

Example 1

To the polymer A obtained in Synthesis Example 1 (100 parts by weight),5 parts by weight of silica hydrophobically-treated withhexamethyldisilazane (Nippon Aerosil Co., Ltd.; product name: R812;particle diameter: 0.007 μm) (as a micronized hydrophobic silica), 20parts by weight of diisodecyl phthalate (product of New Japan ChemicalCo., Ltd.; Sansocizer DIDP) (as a plasticizer), 1 part by weight of abenzotriazole-based ultraviolet absorber (Ciba Specialty Chemicals;product name: TINUVIN 213), 1 part by weight of a hindered amine-basedlight stabilizer (Sankyo Co., Ltd.; product name: Sanol LS765), 2 partsby weight of N-β-aminoethyl-γ-aminopropyltrimethoxysilane (Nippon UnicarCompany Limited; product name: A-1120) (as an adhesion promoter), and 2parts by weight of dibutyltin dilaurate (Sankyo Organic Chemicals Co.,Ltd.; product name: STANN BL) (as a tin curing catalyst) were added, themixture thus obtained was kneaded and defoamed under reduced pressure togenerate a curable composition.

Example 2

A curable composition was obtained in the same manner as in Example 1except that 50 parts by weight of the polymer B obtained in SynthesisExample 2 and 50 parts by weight of the polymer C obtained in SynthesisExample 3 were used in lieu of the polymer A in Example 1, 5 parts byweight of silica hydrophobically-treated with dimethyldisilicone (NipponAerosil Co., Ltd.; product name: RY200S; particle diameter: 0.012 μm)was used in lieu of the silica hydrophobically-treated withhexamethylsilazane, and the amount of diisodecyl phthalate was changedto 10 parts by weight.

Example 3

A curable composition was obtained in the same manner as in Example 2except that 5 parts by weight of silica hydrophobically-treated withhexamethyldisilazane (Nippon Aerosil Co., Ltd.; product name: R812) wasused in lieu of the silica hydrophobically-treated with dimethylsiliconein Example 2.

Example 4

A curable composition was obtained in the same manner as in Example 2except that 5 parts by weight of silica hydrophobically-treated withdimethyldichlorosilane (Nippon Aerosil Co., Ltd.; product name: R972CF;particle diameter: 0.016 μm) was used in lieu of the silicahydrophobically-treated with dimethylsilicone in Example 2.

Example 5

A curable composition was obtained in the same manner as in Example 3except that 10 parts by weight of an acrylic plasticizer (Toagosei Co.,Ltd.; product name: ARUFON UP-1020) was used in lieu of diisodecylphthalate in Example 3.

Example 6

A curable composition was obtained in the same manner as in Example 2except that the amount of diisodecyl phthalate was increased from 10parts by weight in Example 2 to 20 parts by weight, and 5 parts byweight of a graft copolymer (KANEKA CORPORATION; product name: Kane Ace(trademark) FM-20), which is obtained by graft copolymerization of acrosslinkable rubber-like polymer, containing butyl acrylate as a maincomponent, with a vinyl monomer, containing methyl methacrylate andbutyl acrylate as main components, was used in lieu of the silicahydrophobically-treated with dimethylsilicone.

Example 7

A curable composition was obtained in the same manner as in Example 6except that 5 parts by weight of silica hydrophobically-treated withhexamethyldisilazane was further used.

Example 8

A curable composition was obtained in the same manner as in Example 3except that 50 parts by weight of an acrylic-modified polyoxyalkylenepolymer (KANEKA CORPORATION; product name: MS polymer S943) was used inlieu of the polymer C in Example 3.

Comparative Example 1

A curable composition was obtained in the same manner as in Example 1except that the amount of diisodecyl phthalate was changed from 20 partsby weight in Example 1 to 10 parts by weight, and Aerosil R812,hexamethyldisilazane-treated silica, was not used.

Comparative Example 2

A curable composition was obtained in the same manner as in Example 2except that Aerosil RY200S, dimethylsilicone-treated silica, was notused.

Comparative Example 3

A curable composition was obtained in the same manner as in Example 1except that 100 parts by weight of MS polymer S943 was used in lieu ofthe polymer A in Example 1, and the amount of diisodecyl phthalate waschanged from 20 parts by weight to 10 parts by weight.

Comparative Example 4

A curable composition was obtained in the same manner as in Example 2except that 100 parts by weight of the polymer C was used in lieu of thepolymer B and the polymer C.

The above-mentioned curable compositions obtained in Examples 1 to 8 andComparative Examples 1 to 4 were subjected to the following measurementsto evaluate the respective physical properties. The results are shown inTable 1.

(Transparency of the Cured Product)

Each curable composition was spread on a 2 mm-thick acrylic plate by a 5mm spacer under the condition at 23° C. and 50% RH (relative humidity)and the acrylic plate bearing the curable composition in 5 mm thicknesswas put onto a newspaper and the newspaper was observed through thecurable composition and the acrylic plate from above to evaluate thetransparency based on the visibility of letters. The transparency wasevaluated as follows.

Excellent: transparent and letters were clearly seen; Fair: althoughslightly cloudy, letters were readable; Poor: cloudy and letters wereunreadable; and Bad: opaque and letters were unreadable.

(Adhesiveness to Polycarbonate)

Each curable composition was spread in about 5 mm-thickness onto apolycarbonate under the condition at 23° C. and 50% RH and slightlypatted with a microspatula. After 1 week, an about 1 cm cut was formedat the interface between the polycarbonate and the composition with arazor and then the resulting specimen was pulled toward about 180 degreedifferent directions and the broken state was observed. The evaluationwas carried out as follows. CF means good adhesiveness.

CF: breakage of the curable composition, AF: peeling at the interfacebetween the polycarbonate and the composition.

(Viscosity of the Curable Composition)

A 100-cc cup was filled with the curable composition with care to avoidair contamination, and the viscosities at 2 rpm and 10 rpm weremeasured, respectively, under the conditions of 23° C. and 50% RH usingTokimec model BH viscometer and a roter No. 7.

(Workability)

In the case where the ratio (viscosity proportion) calculated bydividing the viscosity value of the curable composition at 2 rpm by thesame at 10 rpm was 1.1 or higher, the workability is determined to beexcellent and in the case where the ratio was lower than 1.1, theworkability was determined to be bad.

(Tensile Properties of the Cured Product)

The curable composition was molded into a sheet-shaped test specimen,about 3 mm in thickness, and the test specimen was cured at 23° C. for 3days and at 50° C. for 4 days and, thereafter, No. 3 JIS dumbbells werepunched out therefrom. They were subjected to tensile testing using aShimadzu Corporation's autograph at a pulling rate of 200 mm/minute (23°C., 50% RH), and the 50% tensile modulus, 100% tensile modulus, strengthat break (Tb) and elongation at break (Eb) were measured.

(Weather Resistance)

The curable composition was molded into a sheet-shaped test specimenwith a thickness of about 3 mm, and the specimen was cured at 23° C. for3 days and at 50° C. for 4 days, then fixed onto an aluminum plate andsubjected to promoted weathering testing using a Suga Test Instruments'sunshine weatherometer (black panel temperature=63° C., water sprayingtime=18 minutes/120 minutes). The surfaces of test specimen wereobserved after irradiation for 500 hours, 1,000 hours, and 3,000 hours.The term “Fair” denotes that the surface retained its initial condition,and “Bad” denotes that cracks were found on the surface.

TABLE 1 Example 1 2 3 4 5 6 7 8 Material Crosslinkable silyl 100composition group-containing vinyl polymer produced by living radicalpolymerization (polymer A) Crosslinkable silyl 50 50 50 50 50 50 50group-containing vinyl polymer produced by living radical polymerization(polymer B) Crosslinkable silyl 50 50 50 50 50 50 group-containingpolyoxyalkylene polymer (polymer C) MS polymer S943 50 Aerosil RY200S 5Aerosil R812 5 5 5 5 5 Aerosil R972CF 5 Kane Ace FM-20 5 5 Diisodecylphthalate 20 10 10 10 20 20 10 (plasticizer) Acrylic plasticizer 10Ultraviolet absorber 1 1 1 1 1 1 1 1 Light stabilizer 1 1 1 1 1 1 1 1Adhesive promoter 2 2 2 2 2 2 2 2 Tin curing catalyst 2 2 2 2 2 2 2 2Transparency of cured product Excellent Fair Fair Excellent Fair FairFair Excellent Adhesiveness to polycarbonate CF CF CF CF CF CF CF CFViscosity  2 rpm (Pa · s) 270 170 70 106 84 228 245 204 10 rpm (Pa · s)188 100 62 85 75 176 190 157 Viscosity proportion (2 rpm/10 rpm) 1.441.70 1.13 1.25 1.12 1.30 1.29 1.30 Workability Fair Fair Fair Fair FairFair Fair Fair Tensile  50% modulus (MPa) 0.1 0.24 0.23 0.25 0.24 0.240.29 0.12 property 100% modulus (MPa) 0.3 0.40 0.39 0.42 0.42 0.43 0.470.23 Strength at break (MPa) 0.4 0.68 0.90 0.79 0.68 0.74 0.95 0.62Elongation at break (%) 143 185 225 205 185 182 193 239 Weather After500-hours- Fair Fair Fair Fair Fair Fair Fair Fair resistanceirradiation by sunshine weatherometer After 1,000-hours- Fair Fair FairFair Fair Fair Fair Fair irradiation by sunshine weatherometer After3,000-hours- Fair Fair Fair Fair Fair Fair Fair Fair irradiation bysunshine weatherometer Comparative Example 1 2 3 4 MaterialCrosslinkable silyl 100 composition group-containing vinyl polymerproduced by living radical polymerization (polymer A) Crosslinkablesilyl 50 group-containing vinyl polymer produced by living radicalpolymerization (polymer B) Crosslinkable silyl 50 100 group-containingpolyoxyalkylene polymer (polymer C) MS polymer S943 100 Aerosil RY200S 5Aerosil R812 5 Aerosil R972CF Kane Ace FM-20 Diisodecyl phthalate 10 1010 10 (plasticizer) Acrylic plasticizer Ultraviolet absorber 1 1 1 1Light stabilizer 1 1 1 1 Adhesive promoter 2 2 2 2 Tin curing catalyst 22 2 2 Transparency of cured product Excellent Fair Excellent PoorAdhesiveness to polycarbonate CF CF CF CF Viscosity  2 rpm (Pa · s) 9224 158 146 10 rpm (Pa · s) 92 23 130 80 Viscosity proportion (2 rpm/10rpm) 1.00 1.04 1.22 1.83 Workability Bad Bad Fair Fair Tensile  50%modulus (MPa) 0.09 0.17 0.18 0.39 property 100% modulus (MPa) 0.15 0.280.30 0.62 Strength at break (MPa) 0.21 0.37 0.83 0.85 Elongation atbreak (%) 147 147 299 167 Weather After 500-hours- Fair Fair Fair Badresistance irradiation by sunshine weatherometer After 1,000-hours- FairFair Bad Bad irradiation by sunshine weatherometer After 3,000-hours-Fair Fair Bad Bad irradiation by sunshine weatherometer

The curable composition obtained in Example 1 was found to have goodworkability and the cured product obtained therefrom was found to betransparent and showed no surface deterioration even after 3,000-hourexposure in a weathering test and thus found to have good weatherresistance. The curable compositions obtained in Examples 2 and 8 werefound giving cured products having remarkably improved strength at breakand elongation at break without deteriorating the transparency andweather resistance by using polyoxyalkylene copolymers in combination.On the other hand, the curable compositions obtained in ComparativeExamples 1 and 2, which did not contain the micronized hydrophobicsilica and the graft copolymer obtained by graft polymerization of acrosslinkable rubber-like acrylic ester polymer and a vinyl monomer,were found to have low ratio (viscosity proportion) of viscosity at 2rpm and viscosity at 10 rpm. In the case of using them as a sealingmaterial for jointing work, they could possibly drip and it is notdesirable. Although the curable compositions obtained in ComparativeExamples 3 and 4, which did not contain the crosslinkablesilyl-containing vinyl polymer produced by living radicalpolymerization, were found to have good transparency and workability andgood tensile properties of the cured products obtained therefrom, thesecompositions were inferior in the weather resistance of the curedproducts obtained therefrom and thus could not stand for long term use.

INDUSTRIAL APPLICABILITY

The curable composition of the invention may be prepared as a onepackage formulation, which can be cured by the reaction with themoisture in the air at room temperature, and is a transparent curablecomposition excellent in strength, elongation at break, weatherresistance, and adhesiveness of the resultant cured product. Further,said curable composition can be suitably used as a transparent adhesive,sealing material and the like.

1. A curable composition which comprises 100 parts by weight of a vinylpolymer (I) the main chain of which is the product of living radicalpolymerization and which contains at least one crosslinkable silylgroup, and 1 to 200 parts by weight of a micronized hydrophobic silica(II).
 2. A curable composition which comprises 100 parts by weight of avinyl polymer (I) the main chain of which is the product of livingradical polymerization and which contains at least one crosslinkablesilyl group, and 1 to 200 parts by weight of a graft copolymer (III)obtained by graft polymerization of a crosslinkable rubber-like acrylicester polymer and a vinyl monomer.
 3. The curable composition accordingto claim 1 wherein the vinyl polymer (I) has a molecular weightdistribution of less than 1.8.
 4. The curable composition according toclaim 1 wherein a vinyl monomer constituting the main chain of the vinylpolymer (I) is mainly selected from the group consisting of(meth)acrylic monomers, acrylonitrile monomers, aromatic vinyl monomers,fluorine-containing vinyl monomers and silicon-containing vinylmonomers.
 5. The curable composition according to claim 1 wherein themain chain of the vinyl polymer (I) is a (meth)acrylic polymer.
 6. Thecurable composition according to claim 1 wherein the main chain of thevinyl polymer (I) is an acrylic polymer.
 7. The curable compositionaccording to claim 6 wherein the main chain of the vinyl polymer (I) isan acrylic ester polymer.
 8. The curable composition according to claim1 wherein the living radical polymerization for producing the main chainof the vinyl polymer (I) is the atom transfer radical polymerization. 9.The curable composition according to claim 8 wherein a metal complexused as the catalyst in the atom transfer radical polymerization is atransition metal complex composed of a VII, VIII, IX, X, or XI groupelement in the periodic table as a central metal.
 10. The curablecomposition according to claim 9 wherein the metal complex used as thecatalyst is a complex composed of copper, nickel, ruthenium or iron as acentral metal.
 11. The curable composition according to claim 10 whereinthe metal complex used as the catalyst is a complex of copper.
 12. Thecurable composition according to claim 1 wherein the crosslinkable silylgroup of the vinyl polymer (I) is represented by the general formula 1:—[Si(R¹)_(2-b)(Y)_(b)O]_(l)—Si(R²)_(3-a)(Y)_(a)  (1) {wherein, R¹ and R²are the same or different and each is an alkyl group containing 1 to 20carbon atoms, an aryl group containing 6 to 20 carbon atoms, an aralkylgroup containing 7 to 20 carbon atoms or a triorganosiloxy grouprepresented by (R′)₃SiO — (in which R′ represents a univalenthydrocarbon group containing 1 to 20 carbon atoms and the three R′groups may be the same or different) and, when there are two or more R¹or R² groups, they may be the same or different; Y represents a hydroxylgroup or a hydrolyzable group and, when there are two or more Y groups,they may be the same or different; a represents 0, 1, 2 or 3, brepresents 0, 1 or 2, and 1 represents an integer of 0 to 19, providedthat the relation a+lb≧1 should be satisfied.}
 13. The curablecomposition according to claim 1 wherein the crosslinkable silyl groupof the vinyl polymer (I) is at the terminus of the main chain.
 14. Thecurable composition according to claim 1 wherein the micronizedhydrophobic silica (II) has a particle diameter of not greater than 0.02μm.
 15. The curable composition according to claim 14 which furthercomprises a polyoxyalkylene polymer (IV) containing at least onecrosslinkable silyl group in an amount within the range of 0.1 to 1,000parts by weight per 100 parts by weight of the vinyl polymer (I). 16.The curable composition according to claim 15 which comprises nopolyoxyalkylene polymer (IV) containing a crosslinkable silyl group(s).17. The curable composition according to claim 16 which furthercomprises 0.1 to 20 parts by weight of a tin curing catalyst (V) per 100parts by weight of the vinyl polymer (I).
 18. An adhesive whichcomprises the curable composition according to claim
 1. 19. (canceled)20. (canceled)
 21. (canceled)
 22. The curable composition according toclaim 2 wherein the vinyl polymer (I) has a molecular weightdistribution of less than 1.8.
 23. The curable composition according toclaim 3 wherein the living radical polymerization for producing the mainchain of the vinyl polymer (I) is the atom transfer radicalpolymerization.